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<title data-rh="true">SLA vs SLO - Alex Ewerlöf Notes</title>
<meta data-rh="true" name="theme-color" content="#001426"/><meta data-rh="true" property="og:type" content="article"/><meta data-rh="true" property="og:title" content="SLA vs SLO"/><meta data-rh="true" name="twitter:title" content="SLA vs SLO"/><meta data-rh="true" name="description" content="Demystify SLA vs. SLO vs. SLI with this expert guide. Learn the critical differences, why they matter in SRE, and how to define them effectively for your services. Essential reading for SREs and engineers."/><meta data-rh="true" property="og:description" content="Demystifying the most common misconception in Service Level jargon"/><meta data-rh="true" name="twitter:description" content="Demystifying the most common misconception in Service Level jargon"/><meta data-rh="true" property="og:image" content="https://substackcdn.com/image/fetch/$s_!qkOK!,w_1200,h_675,c_fill,f_jpg,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png"/><meta data-rh="true" name="twitter:image" content="https://substackcdn.com/image/fetch/$s_!kaFm!,f_auto,q_auto:best,fl_progressive:steep/https%3A%2F%2Falexewerlof.substack.com%2Fapi%2Fv1%2Fpost_preview%2F166314539%2Ftwitter.jpg%3Fversion%3D4"/><meta data-rh="true" name="twitter:card" content="summary_large_image"/><meta data-rh="true" property="article:modified_time" content="2025-06-23T07:48:03.289Z"/>
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class="label">Share</div></button></div></div></div></div><div class="visibility-check"></div><div><div class="dt-post-body"><div class="available-content"><div dir="auto" class="body markup"><p><span>“</span><em>I want all teams to set SLAs between each other</em><span>”, said the leadership.</span></p><p><span>💭 And I thought to myself: “</span><em><span>What are you smoking? I want some of that too! It must be good! What do you mean SLA between teams? Unless one team is literally paying the salary of another team and can take them to court in case of a breach, we’re talking about </span><strong>SLO</strong><span>, not SLA</span></em><span>”!</span></p><ul><li><p>SLA = Service Level Agreement</p></li><li><p>SLO = Service Level Objective</p></li></ul><p>To the untrained eye, the difference is very subtle: just one vowel! Many people, including self-proclaimed SREs use SLA and SLO interchangeably.</p><p>🧐 But once you know the difference, statements like the one I quoted becomes ridiculously funny.</p><p>When I’m hiring SREs, asking the difference between SLA and SLO is my favorite “trick question” because it reveals nuanced knowledge about how reliability is communicated.</p><p>This short post covers:</p><ul><li><p>Why does this distinction matter?</p></li><li><p>An illustration to build a memorable base</p></li><li><p>Quotes from Google’s books</p></li></ul><p>This is not an entry article about SLA or SLO. We have covered those topics before:</p><div data-component-name="DigestPostEmbed" class="digestPostEmbed-flwiST"><a href="https://blog.alexewerlof.com/p/slo" rel="noopener" target="_blank"><div class="pencraft pc-display-flex pc-gap-16 pc-reset"><div style="width:70px;height:70px;" class="pencraft pc-reset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!xH-H!,w_140,h_140,c_fill,f_webp,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0ec62079-bcea-47fa-aafc-e3f7b6ed0f9a_1054x876.png"/><img src="https://substackcdn.com/image/fetch/$s_!xH-H!,w_140,h_140,c_fill,f_auto,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0ec62079-bcea-47fa-aafc-e3f7b6ed0f9a_1054x876.png" sizes="100vw" alt="SLO" width="140" height="140" class="img-OACg1c smSquare-NGbPBa pencraft pc-reset"/></picture></div><div class="pencraft pc-display-flex pc-flexDirection-column pc-reset"><h4 class="pencraft pc-reset color-pub-primary-text-NyXPlw line-height-24-jnGwiv font-display-nhmvtD size-20-P_cSRT weight-bold-DmI9lw reset-IxiVJZ">SLO</h4><div class="pencraft pc-display-flex pc-gap-4 pc-alignItems-center pc-reset"><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA"><a href="https://substack.com/profile/87732486-alex-ewerlof" class="inheritColor-WetTGJ">Alex Ewerlöf</a></div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T reset-IxiVJZ">·</div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA">May 6, 2024</div></div><div class="pencraft pc-display-flex pc-gap-16 pc-paddingTop-0 pc-paddingBottom-0 pc-alignItems-center pc-reset"><a href="https://blog.alexewerlof.com/p/slo" class="pencraft pc-reset align-center-y7ZD4w line-height-20-t4M0El font-text-qe4AeH size-13-hZTUKr weight-medium-fw81nC reset-IxiVJZ"><div class="pencraft pc-display-flex pc-gap-8 pc-alignItems-center pc-reset link-HREYZo"><span class="pencraft pc-reset color-accent-BVX_7M line-height-20-t4M0El font-text-qe4AeH size-14-MLPa7j weight-semibold-uqA4FV reset-IxiVJZ">Read full story</span><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-arrow-right"><path d="M5 12h14"></path><path d="m12 5 7 7-7 7"></path></svg></div></a></div></div></div></a></div><div data-component-name="DigestPostEmbed" class="digestPostEmbed-flwiST"><a href="https://blog.alexewerlof.com/p/sla" rel="noopener" target="_blank"><div class="pencraft pc-display-flex pc-gap-16 pc-reset"><div style="width:70px;height:70px;" class="pencraft pc-reset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!8rTf!,w_140,h_140,c_fill,f_webp,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F9373d220-117e-4814-9a31-428abd3de3c6_1065x822.png"/><img src="https://substackcdn.com/image/fetch/$s_!8rTf!,w_140,h_140,c_fill,f_auto,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F9373d220-117e-4814-9a31-428abd3de3c6_1065x822.png" sizes="100vw" alt="Service Level Agreement" width="140" height="140" class="img-OACg1c smSquare-NGbPBa pencraft pc-reset"/></picture></div><div class="pencraft pc-display-flex pc-flexDirection-column pc-reset"><h4 class="pencraft pc-reset color-pub-primary-text-NyXPlw line-height-24-jnGwiv font-display-nhmvtD size-20-P_cSRT weight-bold-DmI9lw reset-IxiVJZ">Service Level Agreement</h4><div class="pencraft pc-display-flex pc-gap-4 pc-alignItems-center pc-reset"><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA"><a href="https://substack.com/profile/87732486-alex-ewerlof" class="inheritColor-WetTGJ">Alex Ewerlöf</a></div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T reset-IxiVJZ">·</div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA">March 11, 2024</div></div><div class="pencraft pc-display-flex pc-gap-16 pc-paddingTop-0 pc-paddingBottom-0 pc-alignItems-center pc-reset"><a href="https://blog.alexewerlof.com/p/sla" class="pencraft pc-reset align-center-y7ZD4w line-height-20-t4M0El font-text-qe4AeH size-13-hZTUKr weight-medium-fw81nC reset-IxiVJZ"><div class="pencraft pc-display-flex pc-gap-8 pc-alignItems-center pc-reset link-HREYZo"><span class="pencraft pc-reset color-accent-BVX_7M line-height-20-t4M0El font-text-qe4AeH size-14-MLPa7j weight-semibold-uqA4FV reset-IxiVJZ">Read full story</span><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-arrow-right"><path d="M5 12h14"></path><path d="m12 5 7 7-7 7"></path></svg></div></a></div></div></div></a></div><p>As usual, there will be plenty of examples and illustrations to make the abstract topics more approachable.</p><div data-component-name="SubscribeWidget" class="subscribe-widget"><div class="pencraft pc-display-flex pc-justifyContent-center pc-reset"><div class="container-IpPqBD"><form action="/api/v1/free?nojs=true" method="post" novalidate class="form form-M5sC90"><input type="hidden" name="first_url" value/><input type="hidden" name="first_referrer" value/><input type="hidden" name="current_url"/><input type="hidden" name="current_referrer"/><input type="hidden" name="first_session_url" value/><input type="hidden" name="first_session_referrer" value/><input type="hidden" name="referral_code"/><input type="hidden" name="source" value="subscribe-widget"/><input type="hidden" name="referring_pub_id"/><input type="hidden" name="additional_referring_pub_ids"/><input type="hidden" name="source_post_id" value="166314539"/><div class="sideBySideWrap-vGXrwP"><div class="emailInputWrapper-QlA86j"><div class="pencraft pc-display-flex pc-minWidth-0 pc-position-relative pc-reset flex-auto-j3S2WA"><input name="email" placeholder="Type your email..." type="email" class="pencraft emailInput-OkIMeB input-y4v6N4 inputText-pV_yWb"/></div></div><button tabindex="0" type="submit" disabled class="pencraft pc-reset pencraft rightButton primary subscribe-btn button-VFSdkv buttonBase-GK1x3M"><span class="button-text ">Subscribe</span></button></div><div id="error-container"></div></form></div></div></div><h2 class="header-anchor-post">Why does this post exist?<div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§why-does-this-post-exist" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/why-does-this-post-exist" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h2><p>I really didn’t want to write this post because Google SRE books have done a great job of explaining it. But for 2 reasons I have to:</p><ol><li><p>If the point of the language is to communicate, it really pays back to use the correct word. Normally, I wouldn’t care —I’m not a word Nazi. But when building a user facing service, knowing the difference and relationship between SLA and SLO pays back enormously.</p></li><li><p><span>Asking “AI” and searching the internet gets you only so far. </span><a href="https://www.atlassian.com/incident-management/kpis/sla-vs-slo-vs-sli">Atlassian</a><span>, </span><a href="https://www.pagerduty.com/resources/digital-operations/learn/what-is-slo-sla-sli/">PagerDuty</a><span>, and even </span><a href="https://cloud.google.com/blog/products/devops-sre/sre-fundamentals-slis-slas-and-slos">Google</a><span> have pages on the topic but I still haven’t found a resource that is crisp, illustrated, and to the point. I needed something that I could share with people without having to repeat myself again and again. This post exists to scale that ensuing “Aha” moment.</span></p></li></ol><h2 class="header-anchor-post">A visual guide<div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§a-visual-guide" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/a-visual-guide" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h2><p>Sometimes SLI is brought up in comparison to SLA and SLO. We have covered each of them in separate articles.</p><div class="captioned-image-container"><figure><a target="_blank" href="https://substackcdn.com/image/fetch/$s_!8s66!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png" data-component-name="Image2ToDOM" class="image-link image2 is-viewable-img can-restack"><div class="image2-inset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!8s66!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 424w, https://substackcdn.com/image/fetch/$s_!8s66!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 848w, https://substackcdn.com/image/fetch/$s_!8s66!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 1272w, https://substackcdn.com/image/fetch/$s_!8s66!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 1456w" sizes="100vw"/><img src="https://substackcdn.com/image/fetch/$s_!8s66!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png" width="1037" height="860" data-attrs="{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:860,&quot;width&quot;:1037,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:85816,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}" alt srcset="https://substackcdn.com/image/fetch/$s_!8s66!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 424w, https://substackcdn.com/image/fetch/$s_!8s66!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 848w, https://substackcdn.com/image/fetch/$s_!8s66!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 1272w, https://substackcdn.com/image/fetch/$s_!8s66!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 1456w" sizes="100vw" loading="lazy" class="sizing-normal"/></picture><div class="image-link-expand"><div class="pencraft pc-display-flex pc-gap-8 pc-reset"><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container restack-image"><svg aria-hidden="true" width="20" height="20" viewBox="0 0 20 20" fill="none" stroke-width="1.5" stroke="var(--color-fg-primary)" stroke-linecap="round" stroke-linejoin="round" xmlns="http://www.w3.org/2000/svg"><g><path d="M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882"></path></g></svg></button><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container view-image"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-maximize2 lucide-maximize-2"><polyline points="15 3 21 3 21 9"></polyline><polyline points="9 21 3 21 3 15"></polyline><line x1="21" x2="14" y1="3" y2="10"></line><line x1="3" x2="10" y1="21" y2="14"></line></svg></button></div></div></div></a></figure></div><p>In simple terms:</p><ul><li><p><strong><a href="https://blog.alexewerlof.com/p/sli">SLI</a><span>:</span></strong><span> Service Level Indicator → these are just metrics that show how the service consumer perceives reliability of our </span><a href="https://blog.alexewerlof.com/p/service">service</a><span> (not to be confused with microservice or a backend, in Service Level model, a </span><em>service</em><span> refers to a capability or solution for a customer problem).</span></p></li><li><p><a href="https://blog.alexewerlof.com/p/sls">SLS</a><span>: Service Level Status → is the actual value of the indicator in a given time period. If SLI specifies the metric and formula, SLS puts the actual values in it to quantify the reliability and performance of the service.</span></p></li><li><p><strong><a href="https://blog.alexewerlof.com/p/slo">SLO</a><span>:</span></strong><span> Service Level Objective → sets the targets for those metrics in a period of time (like 30 days). As long as SLS is above SLO, we’re good.</span></p></li><li><p><strong><a href="https://blog.alexewerlof.com/p/sla">SLA</a><span>:</span></strong><span> Service Level Agreement → is a legal agreement that connects an external-facing SLI and SLO to financial or legal consequences. This is often the source of confusion and the main reason this article exists.</span></p></li></ul><p>Here’s a visual representation using a gauge as a metaphor for SLI:</p><div class="captioned-image-container"><figure><a target="_blank" href="https://substackcdn.com/image/fetch/$s_!mVzf!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png" data-component-name="Image2ToDOM" class="image-link image2 is-viewable-img can-restack"><div class="image2-inset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!mVzf!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 424w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 848w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 1272w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 1456w" sizes="100vw"/><img src="https://substackcdn.com/image/fetch/$s_!mVzf!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png" width="1038" height="886" data-attrs="{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/c74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:886,&quot;width&quot;:1038,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:130454,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}" alt srcset="https://substackcdn.com/image/fetch/$s_!mVzf!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 424w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 848w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 1272w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 1456w" sizes="100vw" loading="lazy" class="sizing-normal"/></picture><div class="image-link-expand"><div class="pencraft pc-display-flex pc-gap-8 pc-reset"><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container restack-image"><svg aria-hidden="true" width="20" height="20" viewBox="0 0 20 20" fill="none" stroke-width="1.5" stroke="var(--color-fg-primary)" stroke-linecap="round" stroke-linejoin="round" xmlns="http://www.w3.org/2000/svg"><g><path d="M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882"></path></g></svg></button><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container view-image"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-maximize2 lucide-maximize-2"><polyline points="15 3 21 3 21 9"></polyline><polyline points="9 21 3 21 3 15"></polyline><line x1="21" x2="14" y1="3" y2="10"></line><line x1="3" x2="10" y1="21" y2="14"></line></svg></button></div></div></div></a></figure></div><p><span>It can be a bit confusing because SLA </span><em>has</em><span> an SLI and SLO. The best way to think about SLA is as a </span><strong>legal layer on top of SLI and SLO</strong><span>.</span></p><div class="captioned-image-container"><figure><a target="_blank" href="https://substackcdn.com/image/fetch/$s_!1IIW!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png" data-component-name="Image2ToDOM" class="image-link image2 is-viewable-img can-restack"><div class="image2-inset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!1IIW!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 424w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 848w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 1272w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 1456w" sizes="100vw"/><img src="https://substackcdn.com/image/fetch/$s_!1IIW!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png" width="1019" height="980" data-attrs="{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:980,&quot;width&quot;:1019,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:99544,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}" alt srcset="https://substackcdn.com/image/fetch/$s_!1IIW!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 424w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 848w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 1272w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 1456w" sizes="100vw" loading="lazy" class="sizing-normal"/></picture><div class="image-link-expand"><div class="pencraft pc-display-flex pc-gap-8 pc-reset"><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container restack-image"><svg aria-hidden="true" width="20" height="20" viewBox="0 0 20 20" fill="none" stroke-width="1.5" stroke="var(--color-fg-primary)" stroke-linecap="round" stroke-linejoin="round" xmlns="http://www.w3.org/2000/svg"><g><path d="M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882"></path></g></svg></button><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container view-image"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-maximize2 lucide-maximize-2"><polyline points="15 3 21 3 21 9"></polyline><polyline points="9 21 3 21 3 15"></polyline><line x1="21" x2="14" y1="3" y2="10"></line><line x1="3" x2="10" y1="21" y2="14"></line></svg></button></div></div></div></a></figure></div><h2 class="header-anchor-post">What does Google say?<div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§what-does-google-say" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/what-does-google-say" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h2><p><span>We get our first clue in </span><a href="https://sre.google/sre-book/service-level-objectives/">Chapter 4 of Google SRE Book</a><span>:</span></p><blockquote><p><span>… [SLA is] an explicit or implicit </span><strong>contract</strong><span> with your users that includes </span><strong>consequences</strong><span> of meeting (or missing) the SLOs they </span><strong>contain</strong><span>.</span></p></blockquote><p><span>More explicitly, the </span><em>difference</em><span> is in the consequence:</span></p><blockquote><p>The consequences are most easily recognized when they are financial—a rebate or a penalty. </p></blockquote><p>To reduce ambiguity, the book offers a simple mental exercise:</p><blockquote><p><span>An easy way to tell the difference between an SLO and an SLA is to ask, &quot;</span><em>what happens if the SLOs aren’t met</em><span>?&quot;: if there is no explicit consequence, then you are almost certainly looking at an SLO.</span></p></blockquote><p>And here is an example to solidify the difference:</p><blockquote><p><strong>Google Search</strong><span> is an example of an important service that doesn’t have an SLA for the public: we want everyone to use Search as fluidly and efficiently as possible, but we haven’t signed a contract with the whole world.</span></p><p>Even so, there are still consequences if Search isn’t available—unavailability results in a hit to our reputation, as well as a drop in advertising revenue. </p><p><span>Many other Google services, such as </span><strong>Google for Work</strong><span>, do have explicit SLAs with their users. Whether or not a particular service has an SLA, it’s valuable to define SLIs and SLOs and use them to manage the service”</span></p></blockquote><h2 class="header-anchor-post">SLA/SLO in my experience<div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§slaslo-in-my-experience" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/slaslo-in-my-experience" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h2><p><span>There are quite a few pages on the internet about SLA: </span><a href="http://en.wikipedia.org/wiki/Service-level_agreement">Wikipedia</a><span>, </span><a href="https://aws.amazon.com/what-is/service-level-agreement/">Amazon</a><span>, </span><a href="https://www.ibm.com/think/topics/service-level-agreement">IBM</a><span>, </span><a href="https://www.atlassian.com/itsm/service-request-management/slas">Atlassian</a><span>, </span><a href="https://www.salesforce.com/service/service-level-agreement/">SalesForce</a><span>, </span><a href="https://www.zendesk.com/se/blog/keeping-word-support-sla/">ZenDesk</a><span>, …</span></p><p><span>Apart from the fact that some of them parrot each other, the </span><a href="https://sre.google/sre-book/service-level-objectives/">Google SRE book</a><span> remains the undisputable reference. Even then, having helped hundreds of teams to set their SLO and consulted multiple SLAs, I’m opinionated about a few aspects:</span></p><ol><li><p><strong>SLA should be a written legal contract.</strong><span> Google’s definition gives </span><em>implicit</em><span> contracts a pass (e.g. if you say something in a meeting, email, or API documentation), but in my experience SLA is important enough to write a legally binding contract to remove any confusion or interpretation.</span></p></li><li><p><strong>SLA should be explicit and external-facing.</strong><span> Google does a good job clarifying why SLA is external facing but it’s not overly prescriptive about what it actually means. To me, any entity that sells a service should have an SLA that is easy to find and understand. When you buy a pair of speakers online, you check the specifications to know what you’re getting for the money. The same is true for more complex SaaS: as a paying consumer, you have the right to know what level of reliability you’re buying, how much you can depend on it, and what happens if you don’t. Having an SLA is not just goodwill. It can protect the service provider from law suits due to misunderstanding and misalignment of expectations.</span></p></li></ol><p>The confusion between SLA and SLO mainly stems from 2 anti-patterns:</p><ol><li><p><strong>SLO’s that are disconnected from accountability and change management.</strong><span> Some organizations which are at the beginning of their journey to adopt SLOs, only see them as a way to measure and optimize service level. This only utilizes half of their advantage.</span></p><ol><li><p>A good SLO is tied to accountability via alerting. If the service is degrading or disrupting, you want the service owners to be on top of it. Only when the SLO is connected to alerting, it can be taken seriously.</p></li><li><p>The complement of SLO, Error budget, should also be connected to CI/CD to block non-urgent changes. If the service has burned its error budget, change (as the number 1 enemy of reliability) should be blocked in order to stick to the level of commitment made by the SLO. Only when the error budget is used to control risk, it can be taken seriously.</p></li></ol></li><li><p><strong>SLA’s are not seen as external facing legal documents.</strong><span> This comes from poor understanding of the legal side of the SLA. This is sometimes due to how other frameworks like ITIL use SLA loosely for service design.</span></p></li></ol><p>When the SLO is connected to alerting and change management, it has enough consequences to guide the engineers own their service.</p><p>You don’t need to call it an SLA to distinguish serious SLOs from others. If it’s not serious, it shouldn’t be an objective in the first place.</p><p>The word “agreement” is primarily and exclusively reserved for a legal agreement based on my experience.</p><p>The SLA takes much more effort and uses a completely different bag of tricks to protect the service provider from the risks of the service consumer.</p><p>In a future article, we’ll unpack this bag of tricks for both when you’re offerring a SLA or when signing a SLA provided to you. What’s important is to understand that SLA is a completely different beast with different incentives, participants, and guarantees.</p><div data-component-name="SubscribeWidget" class="subscribe-widget"><div class="pencraft pc-display-flex pc-justifyContent-center pc-reset"><div class="container-IpPqBD"><form action="/api/v1/free?nojs=true" method="post" novalidate class="form form-M5sC90"><input type="hidden" name="first_url" value/><input type="hidden" name="first_referrer" value/><input type="hidden" name="current_url"/><input type="hidden" name="current_referrer"/><input type="hidden" name="first_session_url" value/><input type="hidden" name="first_session_referrer" value/><input type="hidden" name="referral_code"/><input type="hidden" name="source" value="subscribe-widget"/><input type="hidden" name="referring_pub_id"/><input type="hidden" name="additional_referring_pub_ids"/><input type="hidden" name="source_post_id" value="166314539"/><div class="sideBySideWrap-vGXrwP"><div class="emailInputWrapper-QlA86j"><div class="pencraft pc-display-flex pc-minWidth-0 pc-position-relative pc-reset flex-auto-j3S2WA"><input name="email" placeholder="Type your email..." type="email" class="pencraft emailInput-OkIMeB input-y4v6N4 inputText-pV_yWb"/></div></div><button tabindex="0" type="submit" disabled class="pencraft pc-reset pencraft rightButton primary subscribe-btn button-VFSdkv buttonBase-GK1x3M"><span class="button-text ">Subscribe</span></button></div><div id="error-container"></div></form></div></div></div><h2 class="header-anchor-post">Similarities and differences between SLA vs SLO<div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§similarities-and-differences-between-sla-vs-slo" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/similarities-and-differences-between-sla-vs-slo" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h2><p>SLA and SLO are related but different:</p><h3 class="header-anchor-post"><strong>Accountability</strong><div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§accountability" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/accountability" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h3><p>Previously we’ve covered the difference between accountability and responsibility.</p><div data-component-name="DigestPostEmbed" class="digestPostEmbed-flwiST"><a href="https://blog.alexewerlof.com/p/accountable-vs-responsible" rel="noopener" target="_blank"><div class="pencraft pc-display-flex pc-gap-16 pc-reset"><div style="width:70px;height:70px;" class="pencraft pc-reset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!RkbM!,w_140,h_140,c_fill,f_webp,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F8d21e22a-ac34-4510-bc50-368c52f6608a_500x673.png"/><img src="https://substackcdn.com/image/fetch/$s_!RkbM!,w_140,h_140,c_fill,f_auto,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F8d21e22a-ac34-4510-bc50-368c52f6608a_500x673.png" sizes="100vw" alt="Accountable vs Responsible" width="140" height="140" class="img-OACg1c smSquare-NGbPBa pencraft pc-reset"/></picture></div><div class="pencraft pc-display-flex pc-flexDirection-column pc-reset"><h4 class="pencraft pc-reset color-pub-primary-text-NyXPlw line-height-24-jnGwiv font-display-nhmvtD size-20-P_cSRT weight-bold-DmI9lw reset-IxiVJZ">Accountable vs Responsible</h4><div class="pencraft pc-display-flex pc-gap-4 pc-alignItems-center pc-reset"><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA"><a href="https://substack.com/profile/87732486-alex-ewerlof" class="inheritColor-WetTGJ">Alex Ewerlöf</a></div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T reset-IxiVJZ">·</div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA">November 29, 2024</div></div><div class="pencraft pc-display-flex pc-gap-16 pc-paddingTop-0 pc-paddingBottom-0 pc-alignItems-center pc-reset"><a href="https://blog.alexewerlof.com/p/accountable-vs-responsible" class="pencraft pc-reset align-center-y7ZD4w line-height-20-t4M0El font-text-qe4AeH size-13-hZTUKr weight-medium-fw81nC reset-IxiVJZ"><div class="pencraft pc-display-flex pc-gap-8 pc-alignItems-center pc-reset link-HREYZo"><span class="pencraft pc-reset color-accent-BVX_7M line-height-20-t4M0El font-text-qe4AeH size-14-MLPa7j weight-semibold-uqA4FV reset-IxiVJZ">Read full story</span><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-arrow-right"><path d="M5 12h14"></path><path d="m12 5 7 7-7 7"></path></svg></div></a></div></div></div></a></div><p>TLDR; it boils down to legal consequences and punishment.</p><ul><li><p><strong>Similarity:</strong><span> Both SLA and SLO communicate measurable service level </span><strong>commitments</strong><span> towards the service consumers.</span></p></li><li><p><strong>SLA:</strong><span> the commitment is typically tied to some financial penalties and entitles the consumer to compensation or legal action in case of a breach.</span></p></li><li><p><strong>SLO:</strong><span> is softer and the consequence of burning the error budget is typically implemented in annoyances like not being able to push new changes to production (change is the number one enemy of reliability: any time you change a system, its likelihood of failure spikes up).</span></p></li></ul><p><span>This difference is small but important because as we discussed in </span><a href="https://blog.alexewerlof.com/p/sla">the article about SLA</a><span>, it boils down to service consumers having leverage or not.</span></p><div class="captioned-image-container"><figure><a target="_blank" href="https://substackcdn.com/image/fetch/$s_!jaaZ!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png" data-component-name="Image2ToDOM" class="image-link image2 is-viewable-img can-restack"><div class="image2-inset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!jaaZ!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 424w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 848w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 1272w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 1456w" sizes="100vw"/><img src="https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png" width="1038" height="809" data-attrs="{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:809,&quot;width&quot;:1038,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:104563,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}" alt srcset="https://substackcdn.com/image/fetch/$s_!jaaZ!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 424w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 848w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 1272w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 1456w" sizes="100vw" loading="lazy" class="sizing-normal"/></picture><div class="image-link-expand"><div class="pencraft pc-display-flex pc-gap-8 pc-reset"><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container restack-image"><svg aria-hidden="true" width="20" height="20" viewBox="0 0 20 20" fill="none" stroke-width="1.5" stroke="var(--color-fg-primary)" stroke-linecap="round" stroke-linejoin="round" xmlns="http://www.w3.org/2000/svg"><g><path d="M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882"></path></g></svg></button><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container view-image"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-maximize2 lucide-maximize-2"><polyline points="15 3 21 3 21 9"></polyline><polyline points="9 21 3 21 3 15"></polyline><line x1="21" x2="14" y1="3" y2="10"></line><line x1="3" x2="10" y1="21" y2="14"></line></svg></button></div></div></div></a></figure></div><h3 class="header-anchor-post"><strong>SLO Target</strong><div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§slo-target" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/slo-target" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h3><p><span>They both set </span><strong>expectations</strong><span> that are set through research and negotiation.</span></p><p><strong>An SLO that is in the SLA</strong><span> promises less reliability than internal SLO because our external commitment should always be lower than what we internally aim for.</span></p><div class="captioned-image-container"><figure><a target="_blank" href="https://substackcdn.com/image/fetch/$s_!qkOK!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png" data-component-name="Image2ToDOM" class="image-link image2 is-viewable-img can-restack"><div class="image2-inset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!qkOK!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 424w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 848w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 1272w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 1456w" sizes="100vw"/><img src="https://substackcdn.com/image/fetch/$s_!qkOK!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png" width="981" height="831" data-attrs="{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/af7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:831,&quot;width&quot;:981,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:137805,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}" alt srcset="https://substackcdn.com/image/fetch/$s_!qkOK!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 424w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 848w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 1272w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 1456w" sizes="100vw" loading="lazy" class="sizing-normal"/></picture><div class="image-link-expand"><div class="pencraft pc-display-flex pc-gap-8 pc-reset"><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container restack-image"><svg aria-hidden="true" width="20" height="20" viewBox="0 0 20 20" fill="none" stroke-width="1.5" stroke="var(--color-fg-primary)" stroke-linecap="round" stroke-linejoin="round" xmlns="http://www.w3.org/2000/svg"><g><path d="M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882"></path></g></svg></button><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container view-image"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-maximize2 lucide-maximize-2"><polyline points="15 3 21 3 21 9"></polyline><polyline points="9 21 3 21 3 15"></polyline><line x1="21" x2="14" y1="3" y2="10"></line><line x1="3" x2="10" y1="21" y2="14"></line></svg></button></div></div></div></a></figure></div><p>For example, if internally we aim for a SLO of 99.99%, the SLA we commit externally may be 99.5% (roughly buying us twice the error budget).</p><p>Under promise and overdeliver, not the other way around.</p><div data-component-name="SubscribeWidget" class="subscribe-widget"><div class="pencraft pc-display-flex pc-justifyContent-center pc-reset"><div class="container-IpPqBD"><form action="/api/v1/free?nojs=true" method="post" novalidate class="form form-M5sC90"><input type="hidden" name="first_url" value/><input type="hidden" name="first_referrer" value/><input type="hidden" name="current_url"/><input type="hidden" name="current_referrer"/><input type="hidden" name="first_session_url" value/><input type="hidden" name="first_session_referrer" value/><input type="hidden" name="referral_code"/><input type="hidden" name="source" value="subscribe-widget"/><input type="hidden" name="referring_pub_id"/><input type="hidden" name="additional_referring_pub_ids"/><input type="hidden" name="source_post_id" value="166314539"/><div class="sideBySideWrap-vGXrwP"><div class="emailInputWrapper-QlA86j"><div class="pencraft pc-display-flex pc-minWidth-0 pc-position-relative pc-reset flex-auto-j3S2WA"><input name="email" placeholder="Type your email..." type="email" class="pencraft emailInput-OkIMeB input-y4v6N4 inputText-pV_yWb"/></div></div><button tabindex="0" type="submit" disabled class="pencraft pc-reset pencraft rightButton primary subscribe-btn button-VFSdkv buttonBase-GK1x3M"><span class="button-text ">Subscribe</span></button></div><div id="error-container"></div></form></div></div></div><p>Regardless of what we aim for, it is always advised to think about the cost of reliability and balance that against the business profit (revenue - expenses) for a given service.</p><p><span>This is the core premise of the 10x/9 rule which elaborates “those 9’s aren’t free!” </span><strong>😃</strong></p><div data-component-name="DigestPostEmbed" class="digestPostEmbed-flwiST"><a href="https://blog.alexewerlof.com/p/10x9" rel="noopener" target="_blank"><div class="pencraft pc-display-flex pc-gap-16 pc-reset"><div style="width:70px;height:70px;" class="pencraft pc-reset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!qHfL!,w_140,h_140,c_fill,f_webp,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fa1d1a58d-cfed-4818-9a2d-125174277f54_1051x577.png"/><img src="https://substackcdn.com/image/fetch/$s_!qHfL!,w_140,h_140,c_fill,f_auto,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fa1d1a58d-cfed-4818-9a2d-125174277f54_1051x577.png" sizes="100vw" alt="10x/9 Rule" width="140" height="140" class="img-OACg1c smSquare-NGbPBa pencraft pc-reset"/></picture></div><div class="pencraft pc-display-flex pc-flexDirection-column pc-reset"><h4 class="pencraft pc-reset color-pub-primary-text-NyXPlw line-height-24-jnGwiv font-display-nhmvtD size-20-P_cSRT weight-bold-DmI9lw reset-IxiVJZ">10x/9 Rule</h4><div class="pencraft pc-display-flex pc-gap-4 pc-alignItems-center pc-reset"><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA"><a href="https://substack.com/profile/87732486-alex-ewerlof" class="inheritColor-WetTGJ">Alex Ewerlöf</a></div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T reset-IxiVJZ">·</div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA">December 1, 2023</div></div><div class="pencraft pc-display-flex pc-gap-16 pc-paddingTop-0 pc-paddingBottom-0 pc-alignItems-center pc-reset"><a href="https://blog.alexewerlof.com/p/10x9" class="pencraft pc-reset align-center-y7ZD4w line-height-20-t4M0El font-text-qe4AeH size-13-hZTUKr weight-medium-fw81nC reset-IxiVJZ"><div class="pencraft pc-display-flex pc-gap-8 pc-alignItems-center pc-reset link-HREYZo"><span class="pencraft pc-reset color-accent-BVX_7M line-height-20-t4M0El font-text-qe4AeH size-14-MLPa7j weight-semibold-uqA4FV reset-IxiVJZ">Read full story</span><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-arrow-right"><path d="M5 12h14"></path><path d="m12 5 7 7-7 7"></path></svg></div></a></div></div></div></a></div><h3 class="header-anchor-post"><strong>Audience</strong><div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§audience" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/audience" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h3><ul><li><p><strong>Similarity:</strong><span> they both set expectations between a service provider and service consumer.</span></p></li><li><p><strong>SLA:</strong><span> the consumer is often an </span><strong>external</strong><span> entity with leverage.</span></p></li><li><p><strong>SLO:</strong><span> the consumer is often </span><strong>internal</strong><span> (e.g., other teams in the same organization).</span></p></li></ul><h3 class="header-anchor-post"><strong>Level of detail</strong><div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§level-of-detail" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/level-of-detail" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h3><ul><li><p><strong>Similarity:</strong><span> They both tie an indicator (metric) to an objective (e.g. 99.9%) but are detailed in different ways.</span></p></li><li><p><strong>External SLIs that are tied to SLA</strong><span> are usually simpler (availability is the most common one). However, SLA has extra details about the legal aspect (consequences, compensations, exceptions, credit, support mechanisms) and typically contains a glossary to build a common language with external consumers. If the service provider is a large vendor, it may get away with having a cookie cutter SLA for all consumers (see </span><a href="https://cloud.google.com/terms/sla">Google Cloud SLA</a><span> for an example).</span></p></li><li><p><strong>Internal SLIs that are only tied to SLOs</strong><span> are more detailed because their primary target are the engineering teams which have a good knowledge about how the service is implemented and consumed. This leads to more nuanced and detailed SLIs that focus on </span><a href="https://blog.alexewerlof.com/p/responsible-for-control">what the team controls</a><span>. In contrast, external SLIs abstract away the shape of the organization and implementation details.</span></p></li></ul><div data-component-name="DigestPostEmbed" class="digestPostEmbed-flwiST"><a href="https://blog.alexewerlof.com/p/responsible-for-control" rel="noopener" target="_blank"><div class="pencraft pc-display-flex pc-gap-16 pc-reset"><div style="width:70px;height:70px;" class="pencraft pc-reset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!18Wx!,w_140,h_140,c_fill,f_webp,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F7855ff73-782f-4250-b6f4-f6bb636d37af_1067x738.png"/><img src="https://substackcdn.com/image/fetch/$s_!18Wx!,w_140,h_140,c_fill,f_auto,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F7855ff73-782f-4250-b6f4-f6bb636d37af_1067x738.png" sizes="100vw" alt="You should never be responsible for what you don't control" width="140" height="140" class="img-OACg1c smSquare-NGbPBa pencraft pc-reset"/></picture></div><div class="pencraft pc-display-flex pc-flexDirection-column pc-reset"><h4 class="pencraft pc-reset color-pub-primary-text-NyXPlw line-height-24-jnGwiv font-display-nhmvtD size-20-P_cSRT weight-bold-DmI9lw reset-IxiVJZ">You should never be responsible for what you don't control</h4><div class="pencraft pc-display-flex pc-gap-4 pc-alignItems-center pc-reset"><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA"><a href="https://substack.com/profile/87732486-alex-ewerlof" class="inheritColor-WetTGJ">Alex Ewerlöf</a></div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T reset-IxiVJZ">·</div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA">February 20, 2024</div></div><div class="pencraft pc-display-flex pc-gap-16 pc-paddingTop-0 pc-paddingBottom-0 pc-alignItems-center pc-reset"><a href="https://blog.alexewerlof.com/p/responsible-for-control" class="pencraft pc-reset align-center-y7ZD4w line-height-20-t4M0El font-text-qe4AeH size-13-hZTUKr weight-medium-fw81nC reset-IxiVJZ"><div class="pencraft pc-display-flex pc-gap-8 pc-alignItems-center pc-reset link-HREYZo"><span class="pencraft pc-reset color-accent-BVX_7M line-height-20-t4M0El font-text-qe4AeH size-14-MLPa7j weight-semibold-uqA4FV reset-IxiVJZ">Read full story</span><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-arrow-right"><path d="M5 12h14"></path><path d="m12 5 7 7-7 7"></path></svg></div></a></div></div></div></a></div><h3 class="header-anchor-post"><strong>Monitoring</strong><div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§monitoring" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/monitoring" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h3><ul><li><p><strong>Similarity:</strong><span> They are both </span><strong>monitored</strong><span> and tied to alerting.</span></p></li><li><p><strong>The SLS of an SLA:</strong><span> may also be tied to a publicly visible status page to help the consumers troubleshoot their system by quickly assessing the reliability of their dependencies. When things fail, the consumers should have an effortless way to answer: “is it me or is it them?” For example, the </span><a href="https://azure.status.microsoft/en-us/status">Azure Status page</a><span> helps their customers to roll out cloud disturbances in case they have an incident. Same with </span><a href="https://www.githubstatus.com/">Github</a><span>, </span><a href="https://slack-status.com/">Slack</a><span>, </span><a href="https://www.google.com/appsstatus/dashboard/">Google</a><span> and a </span><a href="https://github.com/ivbeg/awesome-status-pages">whole bunch of others</a><span>. There are tons of products in this area, and you can even set one up using open-source products like </span><a href="https://cachethq.io/">Cachet</a><span>.</span></p></li><li><p><strong>The SLS of an internal SLO</strong><span> typically misses that public-facing monitoring and is often implemented as an internal dashboard on the observability platform. It requires less effort.</span></p></li></ul><div class="captioned-image-container"><figure><a target="_blank" href="https://substackcdn.com/image/fetch/$s_!91xa!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png" data-component-name="Image2ToDOM" class="image-link image2 is-viewable-img can-restack"><div class="image2-inset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!91xa!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 424w, https://substackcdn.com/image/fetch/$s_!91xa!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 848w, https://substackcdn.com/image/fetch/$s_!91xa!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 1272w, https://substackcdn.com/image/fetch/$s_!91xa!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 1456w" sizes="100vw"/><img src="https://substackcdn.com/image/fetch/$s_!91xa!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png" width="1041" height="968" data-attrs="{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:968,&quot;width&quot;:1041,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:36119,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}" alt srcset="https://substackcdn.com/image/fetch/$s_!91xa!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 424w, https://substackcdn.com/image/fetch/$s_!91xa!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 848w, https://substackcdn.com/image/fetch/$s_!91xa!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 1272w, https://substackcdn.com/image/fetch/$s_!91xa!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 1456w" sizes="100vw" loading="lazy" class="sizing-normal"/></picture><div class="image-link-expand"><div class="pencraft pc-display-flex pc-gap-8 pc-reset"><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container restack-image"><svg aria-hidden="true" width="20" height="20" viewBox="0 0 20 20" fill="none" stroke-width="1.5" stroke="var(--color-fg-primary)" stroke-linecap="round" stroke-linejoin="round" xmlns="http://www.w3.org/2000/svg"><g><path d="M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882"></path></g></svg></button><button tabindex="0" type="button" class="pencraft pc-reset pencraft icon-container view-image"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-maximize2 lucide-maximize-2"><polyline points="15 3 21 3 21 9"></polyline><polyline points="9 21 3 21 3 15"></polyline><line x1="21" x2="14" y1="3" y2="10"></line><line x1="3" x2="10" y1="21" y2="14"></line></svg></button></div></div></div></a><figcaption class="image-caption">aPluse status page on 2025-06-21</figcaption></figure></div><h3 class="header-anchor-post">Purpose<div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§purpose" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/purpose" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h3><ul><li><p><strong>Similarity:</strong><span> They are both used to set expectations.</span></p></li><li><p><strong>SLA</strong><span> is written in a way that protects the service providers’ interest. That is because when the service is </span><a href="https://blog.alexewerlof.com/p/service-degradation-vs-disruption">disrupted or degraded</a><span>, the service provider already looks bad. The last thing it needs is to add insult to the injury and put money on the table.</span></p><div data-component-name="DigestPostEmbed" class="digestPostEmbed-flwiST"><a href="https://blog.alexewerlof.com/p/service-degradation-vs-disruption" rel="noopener" target="_blank"><div class="pencraft pc-display-flex pc-gap-16 pc-reset"><div style="width:70px;height:70px;" class="pencraft pc-reset"><picture><source type="image/webp" srcset="https://substackcdn.com/image/fetch/$s_!wL5v!,w_140,h_140,c_fill,f_webp,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0bd88583-8b9e-4ce0-8cb6-befa958a794f_943x620.png"/><img src="https://substackcdn.com/image/fetch/$s_!wL5v!,w_140,h_140,c_fill,f_auto,q_auto:good,fl_progressive:steep,g_auto/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0bd88583-8b9e-4ce0-8cb6-befa958a794f_943x620.png" sizes="100vw" alt="Degradation vs disruption" width="140" height="140" class="img-OACg1c smSquare-NGbPBa pencraft pc-reset"/></picture></div><div class="pencraft pc-display-flex pc-flexDirection-column pc-reset"><h4 class="pencraft pc-reset color-pub-primary-text-NyXPlw line-height-24-jnGwiv font-display-nhmvtD size-20-P_cSRT weight-bold-DmI9lw reset-IxiVJZ">Degradation vs disruption</h4><div class="pencraft pc-display-flex pc-gap-4 pc-alignItems-center pc-reset"><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA"><a href="https://substack.com/profile/87732486-alex-ewerlof" class="inheritColor-WetTGJ">Alex Ewerlöf</a></div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T reset-IxiVJZ">·</div><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA">July 10, 2024</div></div><div class="pencraft pc-display-flex pc-gap-16 pc-paddingTop-0 pc-paddingBottom-0 pc-alignItems-center pc-reset"><a href="https://blog.alexewerlof.com/p/service-degradation-vs-disruption" class="pencraft pc-reset align-center-y7ZD4w line-height-20-t4M0El font-text-qe4AeH size-13-hZTUKr weight-medium-fw81nC reset-IxiVJZ"><div class="pencraft pc-display-flex pc-gap-8 pc-alignItems-center pc-reset link-HREYZo"><span class="pencraft pc-reset color-accent-BVX_7M line-height-20-t4M0El font-text-qe4AeH size-14-MLPa7j weight-semibold-uqA4FV reset-IxiVJZ">Read full story</span><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-arrow-right"><path d="M5 12h14"></path><path d="m12 5 7 7-7 7"></path></svg></div></a></div></div></div></a></div></li><li><p><strong>Internal SLO</strong><span> is primarily used for giving a focus to service optimization.</span></p></li></ul><blockquote><p><span>… if you can’t ever win a conversation about priorities by quoting a particular SLO, it’s probably not worth having that SLO —</span><a href="https://sre.google/sre-book/service-level-objectives/#id-LvQu7SYSqivIotbub-marker">Google SRE book Chapter 4</a></p></blockquote><h3 class="header-anchor-post"><strong>Revision frequency</strong><div class="pencraft pc-display-flex pc-alignItems-center pc-position-absolute pc-reset header-anchor-parent"><div class="pencraft pc-display-contents pc-reset pubTheme-yiXxQA"><div id="§revision-frequency" class="pencraft pc-reset header-anchor offset-top"></div><button tabindex="0" type="button" aria-label="Link" data-href="https://blog.alexewerlof.com/i/166314539/revision-frequency" class="pencraft pc-reset pencraft iconButton-mq_Et5 iconButtonBase-dJGHgN buttonBase-GK1x3M buttonStyle-r7yGCK size_sm-G3LciD priority_secondary-S63h9o"><svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-link"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></button></div></div></h3><ul><li><p><strong>Similarity:</strong><span> both are subjected to revision and readjustments as the tech evolves and/or the consumer demands changes.</span></p></li><li><p><strong>SLA:</strong><span> is revised less often and is more ceremonial because it involves business stakeholders, legal, and representatives from different parties.</span></p></li><li><p><strong>Internal SLO:</strong><span> can be revised every few months, sometimes weeks. Since its primary consumers are the internal engineers, it may go through rapid evolution to become what makes sense to them. Moreover, the internal stakeholders typically enjoy more flexibility than an external stakeholder to get what they want in a timely manner.</span></p></li></ul><div data-attrs="{&quot;url&quot;:&quot;https://blog.alexewerlof.com/p/sla-vs-slo?utm_source=substack&amp;utm_medium=email&amp;utm_content=share&amp;action=share&quot;,&quot;text&quot;:&quot;Share&quot;}" data-component-name="CaptionedButtonToDOM" class="captioned-button-wrap"><div class="preamble"><p class="cta-caption">If you find this post insightful, please share it in your circles and social media to inspire others.</p></div><p data-attrs="{&quot;url&quot;:&quot;https://blog.alexewerlof.com/p/sla-vs-slo?utm_source=substack&amp;utm_medium=email&amp;utm_content=share&amp;action=share&quot;,&quot;text&quot;:&quot;Share&quot;}" data-component-name="ButtonCreateButton" class="button-wrapper"><a href="https://blog.alexewerlof.com/p/sla-vs-slo?utm_source=substack&amp;utm_medium=email&amp;utm_content=share&amp;action=share" class="button primary"><span>Share</span></a></p></div><div><hr/></div><p><em><a href="https://blog.alexewerlof.com/p/faq#%C2%A7payment">My monetization strategy</a><span> is to give away most content for free. 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class="comment-body expanded"><p><span>I’ve had teams set agreements with each other that specify the consequences if the error budget is depleted. It seemed like it fit the definition of an SLA in principle, but not a legal agreement as defined by this article. In fact, you referenced one of the consequences we used- no features deployed until x,y,z. In which of these acronyms would you classify that? Ok to use SLA? Or is the legal part strict?</span></p></div><div class="pencraft pc-display-flex pc-gap-16 pc-paddingTop-8 pc-justifyContent-flex-start pc-alignItems-center pc-reset comment-actions withShareButton-hQzuEn"><span class="pencraft pc-reset decoration-hover-underline-ClDVRM reset-IxiVJZ"><a class="pencraft pc-reset link-_X6et2 link-LIBpto"><div class="pencraft pc-display-flex pc-gap-6 pc-alignItems-center pc-reset"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="var(--color-fg-secondary-themed)" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-message-circle"><path d="M7.9 20A9 9 0 1 0 4 16.1L2 22Z"></path></svg><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA comment-actions-label">Reply</div></div></a></span><span class="pencraft pc-reset 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https://substackcdn.com/image/fetch/$s_!5gva!,w_96,h_96,c_fill,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc1e33105-166a-4d75-83c9-055eba9146fd_1020x1020.jpeg 3x" width="32" height="32" draggable="false" class="img-OACg1c object-fit-cover-u4ReeV pencraft pc-reset"/></picture></div></div></a></div><div class="pencraft pc-display-flex pc-flexDirection-column pc-reset flex-grow-rzmknG"><div class="pencraft pc-display-flex pc-reset"><div class="pencraft pc-display-flex pc-flexDirection-column pc-gap-4 pc-reset"><div class="pencraft pc-display-flex pc-minWidth-0 pc-gap-8 pc-alignItems-center pc-justifyContent-space-between pc-reset line-height-20-t4M0El font-text-qe4AeH size-15-Psle70 weight-regular-mUq6Gb"><div class="pencraft pc-display-flex pc-minWidth-0 pc-gap-8 pc-alignItems-center pc-reset flex-grow-rzmknG"><div class="pencraft pc-display-flex pc-gap-6 pc-reset color-primary-zABazT line-height-20-t4M0El 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class="comment-body expanded"><p><span>SLO is wrong definition for OLA. </span></p></div><div class="pencraft pc-display-flex pc-gap-16 pc-paddingTop-8 pc-justifyContent-flex-start pc-alignItems-center pc-reset comment-actions withShareButton-hQzuEn"><span class="pencraft pc-reset decoration-hover-underline-ClDVRM reset-IxiVJZ"><a class="pencraft pc-reset link-_X6et2 link-LIBpto"><div class="pencraft pc-display-flex pc-gap-6 pc-alignItems-center pc-reset"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="var(--color-fg-secondary-themed)" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-message-circle"><path d="M7.9 20A9 9 0 1 0 4 16.1L2 22Z"></path></svg><div class="pencraft pc-reset color-pub-secondary-text-hGQ02T line-height-20-t4M0El font-meta-MWBumP size-11-NuY2Zx weight-medium-fw81nC transform-uppercase-yKDgcq reset-IxiVJZ meta-EgzBVA comment-actions-label">Reply</div></div></a></span><span 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I want some of that too! It must be good! What do you mean SLA between teams? Unless one team is literally paying the salary of another team and can take them to court in case of a breach, we\u2019re talking about <strong>SLO</strong>, not SLA</em>\u201D!</p><ul><li><p>SLA = Service Level Agreement</p></li><li><p>SLO = Service Level Objective</p></li></ul><p>To the untrained eye, the difference is very subtle: just one vowel! Many people, including self-proclaimed SREs use SLA and SLO interchangeably.</p><p>\uD83E\uDDD0 But once you know the difference, statements like the one I quoted becomes ridiculously funny.</p><p>When I\u2019m hiring SREs, asking the difference between SLA and SLO is my favorite \u201Ctrick question\u201D because it reveals nuanced knowledge about how reliability is communicated.</p><p>This short post covers:</p><ul><li><p>Why does this distinction matter?</p></li><li><p>An illustration to build a memorable base</p></li><li><p>Quotes from Google\u2019s books</p></li></ul><p>This is not an entry article about SLA or SLO. We have covered those topics before:</p><div class=\\\"digest-post-embed\\\" data-attrs=\\\"{&quot;nodeId&quot;:&quot;85961624-1850-4874-b8d0-7e383854a632&quot;,&quot;caption&quot;:&quot;Service Level Objective (SLO) sets the reliability expectation for the service based on how the service consumer perceives reliability (SLI).&quot;,&quot;cta&quot;:&quot;Read full story&quot;,&quot;showBylines&quot;:true,&quot;showDescription&quot;:true,&quot;showImage&quot;:true,&quot;size&quot;:&quot;sm&quot;,&quot;isEditorNode&quot;:true,&quot;title&quot;:&quot;SLO&quot;,&quot;publishedBylines&quot;:[{&quot;id&quot;:87732486,&quot;name&quot;:&quot;Alex Ewerl\u00F6f&quot;,&quot;bio&quot;:&quot;Writes about technical leadership, growth mindset, and system reliability engineering.\\\\n\\\\nSenior Staff Engineer, MSc Systems Engineering from KTH, Stockholmer, dad, amateur artist.\\\\n\\\\nRead more here: https://www.alexewerlof.com/who&quot;,&quot;photo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Fe2713990-da82-481b-b579-01a7aaa5b85b_560x560.jpeg&quot;,&quot;is_guest&quot;:false,&quot;bestseller_tier&quot;:null}],&quot;post_date&quot;:&quot;2024-05-06T12:45:03.587Z&quot;,&quot;cover_image&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0ec62079-bcea-47fa-aafc-e3f7b6ed0f9a_1054x876.png&quot;,&quot;cover_image_alt&quot;:null,&quot;canonical_url&quot;:&quot;https://blog.alexewerlof.com/p/slo&quot;,&quot;section_name&quot;:&quot;Reliability Engineering&quot;,&quot;video_upload_id&quot;:null,&quot;id&quot;:142248697,&quot;type&quot;:&quot;newsletter&quot;,&quot;reaction_count&quot;:18,&quot;comment_count&quot;:0,&quot;publication_id&quot;:null,&quot;publication_name&quot;:&quot;Alex Ewerl\u00F6f Notes&quot;,&quot;publication_logo_url&quot;:&quot;https://substackcdn.com/image/fetch/$s_!_Ur2!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F8c58cb07-9341-402b-bcdb-9fa767c2cdac_500x500.png&quot;,&quot;belowTheFold&quot;:true,&quot;youtube_url&quot;:null,&quot;show_links&quot;:null,&quot;feed_url&quot;:null}\\\"></div><div class=\\\"digest-post-embed\\\" data-attrs=\\\"{&quot;nodeId&quot;:&quot;f3dd1843-41d5-4332-b252-c68a57f49cc6&quot;,&quot;caption&quot;:&quot;SLA stands for Service Level Agreement. The agreement here refers to a legally binding contract not just a handshake between teams (that\u2019s where internal SLO usually stops).&quot;,&quot;cta&quot;:&quot;Read full story&quot;,&quot;showBylines&quot;:true,&quot;showDescription&quot;:true,&quot;showImage&quot;:true,&quot;size&quot;:&quot;sm&quot;,&quot;isEditorNode&quot;:true,&quot;title&quot;:&quot;Service Level Agreement&quot;,&quot;publishedBylines&quot;:[{&quot;id&quot;:87732486,&quot;name&quot;:&quot;Alex Ewerl\u00F6f&quot;,&quot;bio&quot;:&quot;Writes about technical leadership, growth mindset, and system reliability engineering.\\\\n\\\\nSenior Staff Engineer, MSc Systems Engineering from KTH, Stockholmer, dad, amateur artist.\\\\n\\\\nRead more here: https://www.alexewerlof.com/who&quot;,&quot;photo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Fe2713990-da82-481b-b579-01a7aaa5b85b_560x560.jpeg&quot;,&quot;is_guest&quot;:false,&quot;bestseller_tier&quot;:null}],&quot;post_date&quot;:&quot;2024-03-11T05:30:28.924Z&quot;,&quot;cover_image&quot;:&quot;https://substackcdn.com/image/fetch/$s_!8rTf!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F9373d220-117e-4814-9a31-428abd3de3c6_1065x822.png&quot;,&quot;cover_image_alt&quot;:null,&quot;canonical_url&quot;:&quot;https://blog.alexewerlof.com/p/sla&quot;,&quot;section_name&quot;:&quot;Reliability Engineering&quot;,&quot;video_upload_id&quot;:null,&quot;id&quot;:142293706,&quot;type&quot;:&quot;newsletter&quot;,&quot;reaction_count&quot;:17,&quot;comment_count&quot;:5,&quot;publication_id&quot;:null,&quot;publication_name&quot;:&quot;Alex Ewerl\u00F6f Notes&quot;,&quot;publication_logo_url&quot;:&quot;https://substackcdn.com/image/fetch/$s_!_Ur2!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F8c58cb07-9341-402b-bcdb-9fa767c2cdac_500x500.png&quot;,&quot;belowTheFold&quot;:true,&quot;youtube_url&quot;:null,&quot;show_links&quot;:null,&quot;feed_url&quot;:null}\\\"></div><p>As usual, there will be plenty of examples and illustrations to make the abstract topics more approachable.</p><p class=\\\"button-wrapper\\\" data-attrs=\\\"{&quot;url&quot;:&quot;https://blog.alexewerlof.com/subscribe?&quot;,&quot;text&quot;:&quot;Subscribe now&quot;,&quot;action&quot;:null,&quot;class&quot;:null}\\\" data-component-name=\\\"ButtonCreateButton\\\"><a class=\\\"button primary\\\" href=\\\"https://blog.alexewerlof.com/subscribe?\\\"><span>Subscribe now</span></a></p><h2>Why does this post exist?</h2><p>I really didn\u2019t want to write this post because Google SRE books have done a great job of explaining it. But for 2 reasons I have to:</p><ol><li><p>If the point of the language is to communicate, it really pays back to use the correct word. Normally, I wouldn\u2019t care \u2014I\u2019m not a word Nazi. But when building a user facing service, knowing the difference and relationship between SLA and SLO pays back enormously.</p></li><li><p>Asking \u201CAI\u201D and searching the internet gets you only so far. <a href=\\\"https://www.atlassian.com/incident-management/kpis/sla-vs-slo-vs-sli\\\">Atlassian</a>, <a href=\\\"https://www.pagerduty.com/resources/digital-operations/learn/what-is-slo-sla-sli/\\\">PagerDuty</a>, and even <a href=\\\"https://cloud.google.com/blog/products/devops-sre/sre-fundamentals-slis-slas-and-slos\\\">Google</a> have pages on the topic but I still haven\u2019t found a resource that is crisp, illustrated, and to the point. I needed something that I could share with people without having to repeat myself again and again. This post exists to scale that ensuing \u201CAha\u201D moment.</p></li></ol><h2>A visual guide</h2><p>Sometimes SLI is brought up in comparison to SLA and SLO. We have covered each of them in separate articles.</p><div class=\\\"captioned-image-container\\\"><figure><a class=\\\"image-link image2 is-viewable-img\\\" target=\\\"_blank\\\" href=\\\"https://substackcdn.com/image/fetch/$s_!8s66!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png\\\" data-component-name=\\\"Image2ToDOM\\\"><div class=\\\"image2-inset\\\"><picture><source type=\\\"image/webp\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!8s66!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 424w, https://substackcdn.com/image/fetch/$s_!8s66!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 848w, https://substackcdn.com/image/fetch/$s_!8s66!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 1272w, https://substackcdn.com/image/fetch/$s_!8s66!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 1456w\\\" sizes=\\\"100vw\\\"><img src=\\\"https://substackcdn.com/image/fetch/$s_!8s66!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png\\\" width=\\\"1037\\\" height=\\\"860\\\" data-attrs=\\\"{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:860,&quot;width&quot;:1037,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:85816,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}\\\" class=\\\"sizing-normal\\\" alt=\\\"\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!8s66!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 424w, https://substackcdn.com/image/fetch/$s_!8s66!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 848w, https://substackcdn.com/image/fetch/$s_!8s66!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 1272w, https://substackcdn.com/image/fetch/$s_!8s66!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0e488f68-9532-4c82-86e1-a28883f32806_1037x860.png 1456w\\\" sizes=\\\"100vw\\\" loading=\\\"lazy\\\"></picture><div class=\\\"image-link-expand\\\"><div class=\\\"pencraft pc-display-flex pc-gap-8 pc-reset\\\"><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container restack-image\\\"><svg aria-hidden=\\\"true\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 20 20\\\" fill=\\\"none\\\" stroke-width=\\\"1.5\\\" stroke=\\\"var(--color-fg-primary)\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" xmlns=\\\"http://www.w3.org/2000/svg\\\"><g><path d=\\\"M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882\\\"></path></g></svg></button><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container view-image\\\"><svg xmlns=\\\"http://www.w3.org/2000/svg\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 24 24\\\" fill=\\\"none\\\" stroke=\\\"currentColor\\\" stroke-width=\\\"2\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" class=\\\"lucide lucide-maximize2 lucide-maximize-2\\\"><polyline points=\\\"15 3 21 3 21 9\\\"></polyline><polyline points=\\\"9 21 3 21 3 15\\\"></polyline><line x1=\\\"21\\\" x2=\\\"14\\\" y1=\\\"3\\\" y2=\\\"10\\\"></line><line x1=\\\"3\\\" x2=\\\"10\\\" y1=\\\"21\\\" y2=\\\"14\\\"></line></svg></button></div></div></div></a></figure></div><p>In simple terms:</p><ul><li><p><strong><a href=\\\"https://blog.alexewerlof.com/p/sli\\\">SLI</a>:</strong> Service Level Indicator \u2192 these are just metrics that show how the service consumer perceives reliability of our <a href=\\\"https://blog.alexewerlof.com/p/service\\\">service</a> (not to be confused with microservice or a backend, in Service Level model, a <em>service</em> refers to a capability or solution for a customer problem).</p></li><li><p><a href=\\\"https://blog.alexewerlof.com/p/sls\\\">SLS</a>: Service Level Status \u2192 is the actual value of the indicator in a given time period. If SLI specifies the metric and formula, SLS puts the actual values in it to quantify the reliability and performance of the service.</p></li><li><p><strong><a href=\\\"https://blog.alexewerlof.com/p/slo\\\">SLO</a>:</strong> Service Level Objective \u2192 sets the targets for those metrics in a period of time (like 30 days). As long as SLS is above SLO, we\u2019re good.</p></li><li><p><strong><a href=\\\"https://blog.alexewerlof.com/p/sla\\\">SLA</a>:</strong> Service Level Agreement \u2192 is a legal agreement that connects an external-facing SLI and SLO to financial or legal consequences. This is often the source of confusion and the main reason this article exists.</p></li></ul><p>Here\u2019s a visual representation using a gauge as a metaphor for SLI:</p><div class=\\\"captioned-image-container\\\"><figure><a class=\\\"image-link image2 is-viewable-img\\\" target=\\\"_blank\\\" href=\\\"https://substackcdn.com/image/fetch/$s_!mVzf!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png\\\" data-component-name=\\\"Image2ToDOM\\\"><div class=\\\"image2-inset\\\"><picture><source type=\\\"image/webp\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!mVzf!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 424w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 848w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 1272w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 1456w\\\" sizes=\\\"100vw\\\"><img src=\\\"https://substackcdn.com/image/fetch/$s_!mVzf!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png\\\" width=\\\"1038\\\" height=\\\"886\\\" data-attrs=\\\"{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/c74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:886,&quot;width&quot;:1038,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:130454,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}\\\" class=\\\"sizing-normal\\\" alt=\\\"\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!mVzf!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 424w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 848w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 1272w, https://substackcdn.com/image/fetch/$s_!mVzf!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fc74e18a0-19fe-4ed7-8ab4-0707b22a3180_1038x886.png 1456w\\\" sizes=\\\"100vw\\\" loading=\\\"lazy\\\"></picture><div class=\\\"image-link-expand\\\"><div class=\\\"pencraft pc-display-flex pc-gap-8 pc-reset\\\"><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container restack-image\\\"><svg aria-hidden=\\\"true\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 20 20\\\" fill=\\\"none\\\" stroke-width=\\\"1.5\\\" stroke=\\\"var(--color-fg-primary)\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" xmlns=\\\"http://www.w3.org/2000/svg\\\"><g><path d=\\\"M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882\\\"></path></g></svg></button><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container view-image\\\"><svg xmlns=\\\"http://www.w3.org/2000/svg\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 24 24\\\" fill=\\\"none\\\" stroke=\\\"currentColor\\\" stroke-width=\\\"2\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" class=\\\"lucide lucide-maximize2 lucide-maximize-2\\\"><polyline points=\\\"15 3 21 3 21 9\\\"></polyline><polyline points=\\\"9 21 3 21 3 15\\\"></polyline><line x1=\\\"21\\\" x2=\\\"14\\\" y1=\\\"3\\\" y2=\\\"10\\\"></line><line x1=\\\"3\\\" x2=\\\"10\\\" y1=\\\"21\\\" y2=\\\"14\\\"></line></svg></button></div></div></div></a></figure></div><p>It can be a bit confusing because SLA <em>has</em> an SLI and SLO. The best way to think about SLA is as a <strong>legal layer on top of SLI and SLO</strong>.</p><div class=\\\"captioned-image-container\\\"><figure><a class=\\\"image-link image2 is-viewable-img\\\" target=\\\"_blank\\\" href=\\\"https://substackcdn.com/image/fetch/$s_!1IIW!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png\\\" data-component-name=\\\"Image2ToDOM\\\"><div class=\\\"image2-inset\\\"><picture><source type=\\\"image/webp\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!1IIW!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 424w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 848w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 1272w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 1456w\\\" sizes=\\\"100vw\\\"><img src=\\\"https://substackcdn.com/image/fetch/$s_!1IIW!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png\\\" width=\\\"1019\\\" height=\\\"980\\\" data-attrs=\\\"{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:980,&quot;width&quot;:1019,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:99544,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}\\\" class=\\\"sizing-normal\\\" alt=\\\"\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!1IIW!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 424w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 848w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 1272w, https://substackcdn.com/image/fetch/$s_!1IIW!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F2efa196b-e9e0-4fec-a832-e0418d233e52_1019x980.png 1456w\\\" sizes=\\\"100vw\\\" loading=\\\"lazy\\\"></picture><div class=\\\"image-link-expand\\\"><div class=\\\"pencraft pc-display-flex pc-gap-8 pc-reset\\\"><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container restack-image\\\"><svg aria-hidden=\\\"true\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 20 20\\\" fill=\\\"none\\\" stroke-width=\\\"1.5\\\" stroke=\\\"var(--color-fg-primary)\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" xmlns=\\\"http://www.w3.org/2000/svg\\\"><g><path d=\\\"M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882\\\"></path></g></svg></button><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container view-image\\\"><svg xmlns=\\\"http://www.w3.org/2000/svg\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 24 24\\\" fill=\\\"none\\\" stroke=\\\"currentColor\\\" stroke-width=\\\"2\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" class=\\\"lucide lucide-maximize2 lucide-maximize-2\\\"><polyline points=\\\"15 3 21 3 21 9\\\"></polyline><polyline points=\\\"9 21 3 21 3 15\\\"></polyline><line x1=\\\"21\\\" x2=\\\"14\\\" y1=\\\"3\\\" y2=\\\"10\\\"></line><line x1=\\\"3\\\" x2=\\\"10\\\" y1=\\\"21\\\" y2=\\\"14\\\"></line></svg></button></div></div></div></a></figure></div><h2>What does Google say?</h2><p>We get our first clue in <a href=\\\"https://sre.google/sre-book/service-level-objectives/\\\">Chapter 4 of Google SRE Book</a>:</p><blockquote><p>\u2026 [SLA is] an explicit or implicit <strong>contract</strong> with your users that includes <strong>consequences</strong> of meeting (or missing) the SLOs they <strong>contain</strong>.</p></blockquote><p>More explicitly, the <em>difference</em> is in the consequence:</p><blockquote><p>The consequences are most easily recognized when they are financial\u2014a rebate or a penalty. </p></blockquote><p>To reduce ambiguity, the book offers a simple mental exercise:</p><blockquote><p>An easy way to tell the difference between an SLO and an SLA is to ask, \\\"<em>what happens if the SLOs aren\u2019t met</em>?\\\": if there is no explicit consequence, then you are almost certainly looking at an SLO.</p></blockquote><p>And here is an example to solidify the difference:</p><blockquote><p><strong>Google Search</strong> is an example of an important service that doesn\u2019t have an SLA for the public: we want everyone to use Search as fluidly and efficiently as possible, but we haven\u2019t signed a contract with the whole world.</p><p>Even so, there are still consequences if Search isn\u2019t available\u2014unavailability results in a hit to our reputation, as well as a drop in advertising revenue. </p><p>Many other Google services, such as <strong>Google for Work</strong>, do have explicit SLAs with their users. Whether or not a particular service has an SLA, it\u2019s valuable to define SLIs and SLOs and use them to manage the service\u201D</p></blockquote><h2>SLA/SLO in my experience</h2><p>There are quite a few pages on the internet about SLA: <a href=\\\"http://en.wikipedia.org/wiki/Service-level_agreement\\\">Wikipedia</a>, <a href=\\\"https://aws.amazon.com/what-is/service-level-agreement/\\\">Amazon</a>, <a href=\\\"https://www.ibm.com/think/topics/service-level-agreement\\\">IBM</a>, <a href=\\\"https://www.atlassian.com/itsm/service-request-management/slas\\\">Atlassian</a>, <a href=\\\"https://www.salesforce.com/service/service-level-agreement/\\\">SalesForce</a>, <a href=\\\"https://www.zendesk.com/se/blog/keeping-word-support-sla/\\\">ZenDesk</a>, \u2026</p><p>Apart from the fact that some of them parrot each other, the <a href=\\\"https://sre.google/sre-book/service-level-objectives/\\\">Google SRE book</a> remains the undisputable reference. Even then, having helped hundreds of teams to set their SLO and consulted multiple SLAs, I\u2019m opinionated about a few aspects:</p><ol><li><p><strong>SLA should be a written legal contract.</strong> Google\u2019s definition gives <em>implicit</em> contracts a pass (e.g. if you say something in a meeting, email, or API documentation), but in my experience SLA is important enough to write a legally binding contract to remove any confusion or interpretation.</p></li><li><p><strong>SLA should be explicit and external-facing.</strong> Google does a good job clarifying why SLA is external facing but it\u2019s not overly prescriptive about what it actually means. To me, any entity that sells a service should have an SLA that is easy to find and understand. When you buy a pair of speakers online, you check the specifications to know what you\u2019re getting for the money. The same is true for more complex SaaS: as a paying consumer, you have the right to know what level of reliability you\u2019re buying, how much you can depend on it, and what happens if you don\u2019t. Having an SLA is not just goodwill. It can protect the service provider from law suits due to misunderstanding and misalignment of expectations.</p></li></ol><p>The confusion between SLA and SLO mainly stems from 2 anti-patterns:</p><ol><li><p><strong>SLO\u2019s that are disconnected from accountability and change management.</strong> Some organizations which are at the beginning of their journey to adopt SLOs, only see them as a way to measure and optimize service level. This only utilizes half of their advantage.</p><ol><li><p>A good SLO is tied to accountability via alerting. If the service is degrading or disrupting, you want the service owners to be on top of it. Only when the SLO is connected to alerting, it can be taken seriously.</p></li><li><p>The complement of SLO, Error budget, should also be connected to CI/CD to block non-urgent changes. If the service has burned its error budget, change (as the number 1 enemy of reliability) should be blocked in order to stick to the level of commitment made by the SLO. Only when the error budget is used to control risk, it can be taken seriously.</p></li></ol></li><li><p><strong>SLA\u2019s are not seen as external facing legal documents.</strong> This comes from poor understanding of the legal side of the SLA. This is sometimes due to how other frameworks like ITIL use SLA loosely for service design.</p></li></ol><p>When the SLO is connected to alerting and change management, it has enough consequences to guide the engineers own their service.</p><p>You don\u2019t need to call it an SLA to distinguish serious SLOs from others. If it\u2019s not serious, it shouldn\u2019t be an objective in the first place.</p><p>The word \u201Cagreement\u201D is primarily and exclusively reserved for a legal agreement based on my experience.</p><p>The SLA takes much more effort and uses a completely different bag of tricks to protect the service provider from the risks of the service consumer.</p><p>In a future article, we\u2019ll unpack this bag of tricks for both when you\u2019re offerring a SLA or when signing a SLA provided to you. What\u2019s important is to understand that SLA is a completely different beast with different incentives, participants, and guarantees.</p><p class=\\\"button-wrapper\\\" data-attrs=\\\"{&quot;url&quot;:&quot;https://blog.alexewerlof.com/subscribe?&quot;,&quot;text&quot;:&quot;Subscribe now&quot;,&quot;action&quot;:null,&quot;class&quot;:null}\\\" data-component-name=\\\"ButtonCreateButton\\\"><a class=\\\"button primary\\\" href=\\\"https://blog.alexewerlof.com/subscribe?\\\"><span>Subscribe now</span></a></p><h2>Similarities and differences between SLA vs SLO</h2><p>SLA and SLO are related but different:</p><h3><strong>Accountability</strong></h3><p>Previously we\u2019ve covered the difference between accountability and responsibility.</p><div class=\\\"digest-post-embed\\\" data-attrs=\\\"{&quot;nodeId&quot;:&quot;4d12b9f9-1b6a-4579-965f-c0d9cdaa5dbc&quot;,&quot;caption&quot;:&quot;English isn\u2019t my native tongue. I didn\u2019t know the difference between these accountability and responsibility until my ownership trio was pretty popular. TLDR; here\u2019s the summary:&quot;,&quot;cta&quot;:&quot;Read full story&quot;,&quot;showBylines&quot;:true,&quot;showDescription&quot;:true,&quot;showImage&quot;:true,&quot;size&quot;:&quot;sm&quot;,&quot;isEditorNode&quot;:true,&quot;title&quot;:&quot;Accountable vs Responsible&quot;,&quot;publishedBylines&quot;:[{&quot;id&quot;:87732486,&quot;name&quot;:&quot;Alex Ewerl\u00F6f&quot;,&quot;bio&quot;:&quot;Writes about technical leadership, growth mindset, and system reliability engineering.\\\\n\\\\nSenior Staff Engineer, MSc Systems Engineering from KTH, Stockholmer, dad, amateur artist.\\\\n\\\\nRead more here: https://www.alexewerlof.com/who&quot;,&quot;photo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Fe2713990-da82-481b-b579-01a7aaa5b85b_560x560.jpeg&quot;,&quot;is_guest&quot;:false,&quot;bestseller_tier&quot;:null}],&quot;post_date&quot;:&quot;2024-11-29T09:22:15.595Z&quot;,&quot;cover_image&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F8d21e22a-ac34-4510-bc50-368c52f6608a_500x673.png&quot;,&quot;cover_image_alt&quot;:null,&quot;canonical_url&quot;:&quot;https://blog.alexewerlof.com/p/accountable-vs-responsible&quot;,&quot;section_name&quot;:&quot;Technical Leadership&quot;,&quot;video_upload_id&quot;:null,&quot;id&quot;:152293327,&quot;type&quot;:&quot;newsletter&quot;,&quot;reaction_count&quot;:13,&quot;comment_count&quot;:0,&quot;publication_id&quot;:null,&quot;publication_name&quot;:&quot;Alex Ewerl\u00F6f Notes&quot;,&quot;publication_logo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F8c58cb07-9341-402b-bcdb-9fa767c2cdac_500x500.png&quot;,&quot;belowTheFold&quot;:true,&quot;youtube_url&quot;:null,&quot;show_links&quot;:null,&quot;feed_url&quot;:null}\\\"></div><p>TLDR; it boils down to legal consequences and punishment.</p><ul><li><p><strong>Similarity:</strong> Both SLA and SLO communicate measurable service level <strong>commitments</strong> towards the service consumers.</p></li><li><p><strong>SLA:</strong> the commitment is typically tied to some financial penalties and entitles the consumer to compensation or legal action in case of a breach.</p></li><li><p><strong>SLO:</strong> is softer and the consequence of burning the error budget is typically implemented in annoyances like not being able to push new changes to production (change is the number one enemy of reliability: any time you change a system, its likelihood of failure spikes up).</p></li></ul><p>This difference is small but important because as we discussed in <a href=\\\"https://blog.alexewerlof.com/p/sla\\\">the article about SLA</a>, it boils down to service consumers having leverage or not.</p><div class=\\\"captioned-image-container\\\"><figure><a class=\\\"image-link image2 is-viewable-img\\\" target=\\\"_blank\\\" href=\\\"https://substackcdn.com/image/fetch/$s_!jaaZ!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png\\\" data-component-name=\\\"Image2ToDOM\\\"><div class=\\\"image2-inset\\\"><picture><source type=\\\"image/webp\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!jaaZ!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 424w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 848w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 1272w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 1456w\\\" sizes=\\\"100vw\\\"><img src=\\\"https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png\\\" width=\\\"1038\\\" height=\\\"809\\\" 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srcset=\\\"https://substackcdn.com/image/fetch/$s_!jaaZ!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 424w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 848w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 1272w, https://substackcdn.com/image/fetch/$s_!jaaZ!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F1414d38b-1bc6-4357-827f-74adb46065bb_1038x809.png 1456w\\\" sizes=\\\"100vw\\\" loading=\\\"lazy\\\"></picture><div class=\\\"image-link-expand\\\"><div class=\\\"pencraft pc-display-flex pc-gap-8 pc-reset\\\"><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container restack-image\\\"><svg aria-hidden=\\\"true\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 20 20\\\" fill=\\\"none\\\" stroke-width=\\\"1.5\\\" stroke=\\\"var(--color-fg-primary)\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" xmlns=\\\"http://www.w3.org/2000/svg\\\"><g><path d=\\\"M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882\\\"></path></g></svg></button><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container view-image\\\"><svg xmlns=\\\"http://www.w3.org/2000/svg\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 24 24\\\" fill=\\\"none\\\" stroke=\\\"currentColor\\\" stroke-width=\\\"2\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" class=\\\"lucide lucide-maximize2 lucide-maximize-2\\\"><polyline points=\\\"15 3 21 3 21 9\\\"></polyline><polyline points=\\\"9 21 3 21 3 15\\\"></polyline><line x1=\\\"21\\\" x2=\\\"14\\\" y1=\\\"3\\\" y2=\\\"10\\\"></line><line x1=\\\"3\\\" x2=\\\"10\\\" y1=\\\"21\\\" y2=\\\"14\\\"></line></svg></button></div></div></div></a></figure></div><h3><strong>SLO Target</strong></h3><p>They both set <strong>expectations</strong> that are set through research and negotiation.</p><p><strong>An SLO that is in the SLA</strong> promises less reliability than internal SLO because our external commitment should always be lower than what we internally aim for.</p><div class=\\\"captioned-image-container\\\"><figure><a class=\\\"image-link image2 is-viewable-img\\\" target=\\\"_blank\\\" href=\\\"https://substackcdn.com/image/fetch/$s_!qkOK!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png\\\" data-component-name=\\\"Image2ToDOM\\\"><div class=\\\"image2-inset\\\"><picture><source type=\\\"image/webp\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!qkOK!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 424w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 848w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_1272,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 1272w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_1456,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 1456w\\\" sizes=\\\"100vw\\\"><img src=\\\"https://substackcdn.com/image/fetch/$s_!qkOK!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png\\\" width=\\\"981\\\" height=\\\"831\\\" data-attrs=\\\"{&quot;src&quot;:&quot;https://substack-post-media.s3.amazonaws.com/public/images/af7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png&quot;,&quot;srcNoWatermark&quot;:null,&quot;fullscreen&quot;:null,&quot;imageSize&quot;:null,&quot;height&quot;:831,&quot;width&quot;:981,&quot;resizeWidth&quot;:null,&quot;bytes&quot;:137805,&quot;alt&quot;:null,&quot;title&quot;:null,&quot;type&quot;:&quot;image/png&quot;,&quot;href&quot;:null,&quot;belowTheFold&quot;:true,&quot;topImage&quot;:false,&quot;internalRedirect&quot;:&quot;https://blog.alexewerlof.com/i/166314539?img=https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png&quot;,&quot;isProcessing&quot;:false,&quot;align&quot;:null,&quot;offset&quot;:false}\\\" class=\\\"sizing-normal\\\" alt=\\\"\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!qkOK!,w_424,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 424w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_848,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 848w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_1272,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 1272w, https://substackcdn.com/image/fetch/$s_!qkOK!,w_1456,c_limit,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Faf7976ea-5a03-409c-b1a1-7ba79686a90a_981x831.png 1456w\\\" sizes=\\\"100vw\\\" loading=\\\"lazy\\\"></picture><div class=\\\"image-link-expand\\\"><div class=\\\"pencraft pc-display-flex pc-gap-8 pc-reset\\\"><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container restack-image\\\"><svg aria-hidden=\\\"true\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 20 20\\\" fill=\\\"none\\\" stroke-width=\\\"1.5\\\" stroke=\\\"var(--color-fg-primary)\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" xmlns=\\\"http://www.w3.org/2000/svg\\\"><g><path d=\\\"M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882\\\"></path></g></svg></button><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container view-image\\\"><svg xmlns=\\\"http://www.w3.org/2000/svg\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 24 24\\\" fill=\\\"none\\\" stroke=\\\"currentColor\\\" stroke-width=\\\"2\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" class=\\\"lucide lucide-maximize2 lucide-maximize-2\\\"><polyline points=\\\"15 3 21 3 21 9\\\"></polyline><polyline points=\\\"9 21 3 21 3 15\\\"></polyline><line x1=\\\"21\\\" x2=\\\"14\\\" y1=\\\"3\\\" y2=\\\"10\\\"></line><line x1=\\\"3\\\" x2=\\\"10\\\" y1=\\\"21\\\" y2=\\\"14\\\"></line></svg></button></div></div></div></a></figure></div><p>For example, if internally we aim for a SLO of 99.99%, the SLA we commit externally may be 99.5% (roughly buying us twice the error budget).</p><p>Under promise and overdeliver, not the other way around.</p><p class=\\\"button-wrapper\\\" data-attrs=\\\"{&quot;url&quot;:&quot;https://blog.alexewerlof.com/subscribe?&quot;,&quot;text&quot;:&quot;Subscribe now&quot;,&quot;action&quot;:null,&quot;class&quot;:null}\\\" data-component-name=\\\"ButtonCreateButton\\\"><a class=\\\"button primary\\\" href=\\\"https://blog.alexewerlof.com/subscribe?\\\"><span>Subscribe now</span></a></p><p>Regardless of what we aim for, it is always advised to think about the cost of reliability and balance that against the business profit (revenue - expenses) for a given service.</p><p>This is the core premise of the 10x/9 rule which elaborates \u201Cthose 9\u2019s aren\u2019t free!\u201D <strong>\uD83D\uDE03</strong></p><div class=\\\"digest-post-embed\\\" data-attrs=\\\"{&quot;nodeId&quot;:&quot;48d2ae23-1881-4f42-b1fd-7b86672b6f08&quot;,&quot;caption&quot;:&quot;When setting SLOs (service level objectives) there\u2019s a rule of thumb that goes like this:&quot;,&quot;cta&quot;:&quot;Read full story&quot;,&quot;showBylines&quot;:true,&quot;showDescription&quot;:true,&quot;showImage&quot;:true,&quot;size&quot;:&quot;sm&quot;,&quot;isEditorNode&quot;:true,&quot;title&quot;:&quot;10x/9 Rule&quot;,&quot;publishedBylines&quot;:[{&quot;id&quot;:87732486,&quot;name&quot;:&quot;Alex Ewerl\u00F6f&quot;,&quot;bio&quot;:&quot;Writes about technical leadership, growth mindset, and system reliability engineering.\\\\n\\\\nSenior Staff Engineer, MSc Systems Engineering from KTH, Stockholmer, dad, amateur artist.\\\\n\\\\nRead more here: https://www.alexewerlof.com/who&quot;,&quot;photo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Fe2713990-da82-481b-b579-01a7aaa5b85b_560x560.jpeg&quot;,&quot;is_guest&quot;:false,&quot;bestseller_tier&quot;:null}],&quot;post_date&quot;:&quot;2023-12-01T05:30:17.586Z&quot;,&quot;cover_image&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fa1d1a58d-cfed-4818-9a2d-125174277f54_1051x577.png&quot;,&quot;cover_image_alt&quot;:null,&quot;canonical_url&quot;:&quot;https://blog.alexewerlof.com/p/10x9&quot;,&quot;section_name&quot;:&quot;Reliability Engineering&quot;,&quot;video_upload_id&quot;:null,&quot;id&quot;:139126336,&quot;type&quot;:&quot;newsletter&quot;,&quot;reaction_count&quot;:6,&quot;comment_count&quot;:0,&quot;publication_id&quot;:null,&quot;publication_name&quot;:&quot;Alex Ewerl\u00F6f Notes&quot;,&quot;publication_logo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F8c58cb07-9341-402b-bcdb-9fa767c2cdac_500x500.png&quot;,&quot;belowTheFold&quot;:true,&quot;youtube_url&quot;:null,&quot;show_links&quot;:null,&quot;feed_url&quot;:null}\\\"></div><h3><strong>Audience</strong></h3><ul><li><p><strong>Similarity:</strong> they both set expectations between a service provider and service consumer.</p></li><li><p><strong>SLA:</strong> the consumer is often an <strong>external</strong> entity with leverage.</p></li><li><p><strong>SLO:</strong> the consumer is often <strong>internal</strong> (e.g., other teams in the same organization).</p></li></ul><h3><strong>Level of detail</strong></h3><ul><li><p><strong>Similarity:</strong> They both tie an indicator (metric) to an objective (e.g. 99.9%) but are detailed in different ways.</p></li><li><p><strong>External SLIs that are tied to SLA</strong> are usually simpler (availability is the most common one). However, SLA has extra details about the legal aspect (consequences, compensations, exceptions, credit, support mechanisms) and typically contains a glossary to build a common language with external consumers. If the service provider is a large vendor, it may get away with having a cookie cutter SLA for all consumers (see <a href=\\\"https://cloud.google.com/terms/sla\\\">Google Cloud SLA</a> for an example).</p></li><li><p><strong>Internal SLIs that are only tied to SLOs</strong> are more detailed because their primary target are the engineering teams which have a good knowledge about how the service is implemented and consumed. This leads to more nuanced and detailed SLIs that focus on <a href=\\\"https://blog.alexewerlof.com/p/responsible-for-control\\\">what the team controls</a>. In contrast, external SLIs abstract away the shape of the organization and implementation details.</p></li></ul><div class=\\\"digest-post-embed\\\" data-attrs=\\\"{&quot;nodeId&quot;:&quot;3f4ddadf-8586-4813-8e36-b07f4aece7bc&quot;,&quot;caption&quot;:&quot;One of my favorite sentences to say during Service Level Workshops is:&quot;,&quot;cta&quot;:&quot;Read full story&quot;,&quot;showBylines&quot;:true,&quot;showDescription&quot;:true,&quot;showImage&quot;:true,&quot;size&quot;:&quot;sm&quot;,&quot;isEditorNode&quot;:true,&quot;title&quot;:&quot;You should never be responsible for what you don't control&quot;,&quot;publishedBylines&quot;:[{&quot;id&quot;:87732486,&quot;name&quot;:&quot;Alex Ewerl\u00F6f&quot;,&quot;bio&quot;:&quot;Writes about technical leadership, growth mindset, and system reliability engineering.\\\\n\\\\nSenior Staff Engineer, MSc Systems Engineering from KTH, Stockholmer, dad, amateur artist.\\\\n\\\\nRead more here: https://www.alexewerlof.com/who&quot;,&quot;photo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Fe2713990-da82-481b-b579-01a7aaa5b85b_560x560.jpeg&quot;,&quot;is_guest&quot;:false,&quot;bestseller_tier&quot;:null}],&quot;post_date&quot;:&quot;2024-02-20T18:54:47.854Z&quot;,&quot;cover_image&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F7855ff73-782f-4250-b6f4-f6bb636d37af_1067x738.png&quot;,&quot;cover_image_alt&quot;:null,&quot;canonical_url&quot;:&quot;https://blog.alexewerlof.com/p/responsible-for-control&quot;,&quot;section_name&quot;:&quot;Reliability Engineering&quot;,&quot;video_upload_id&quot;:null,&quot;id&quot;:141855236,&quot;type&quot;:&quot;newsletter&quot;,&quot;reaction_count&quot;:19,&quot;comment_count&quot;:0,&quot;publication_id&quot;:null,&quot;publication_name&quot;:&quot;Alex Ewerl\u00F6f Notes&quot;,&quot;publication_logo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F8c58cb07-9341-402b-bcdb-9fa767c2cdac_500x500.png&quot;,&quot;belowTheFold&quot;:true,&quot;youtube_url&quot;:null,&quot;show_links&quot;:null,&quot;feed_url&quot;:null}\\\"></div><h3><strong>Monitoring</strong></h3><ul><li><p><strong>Similarity:</strong> They are both <strong>monitored</strong> and tied to alerting.</p></li><li><p><strong>The SLS of an SLA:</strong> may also be tied to a publicly visible status page to help the consumers troubleshoot their system by quickly assessing the reliability of their dependencies. When things fail, the consumers should have an effortless way to answer: \u201Cis it me or is it them?\u201D For example, the <a href=\\\"https://azure.status.microsoft/en-us/status\\\">Azure Status page</a> helps their customers to roll out cloud disturbances in case they have an incident. Same with <a href=\\\"https://www.githubstatus.com/\\\">Github</a>, <a href=\\\"https://slack-status.com/\\\">Slack</a>, <a href=\\\"https://www.google.com/appsstatus/dashboard/\\\">Google</a> and a <a href=\\\"https://github.com/ivbeg/awesome-status-pages\\\">whole bunch of others</a>. There are tons of products in this area, and you can even set one up using open-source products like <a href=\\\"https://cachethq.io/\\\">Cachet</a>.</p></li><li><p><strong>The SLS of an internal SLO</strong> typically misses that public-facing monitoring and is often implemented as an internal dashboard on the observability platform. It requires less effort.</p></li></ul><div class=\\\"captioned-image-container\\\"><figure><a class=\\\"image-link image2 is-viewable-img\\\" target=\\\"_blank\\\" href=\\\"https://substackcdn.com/image/fetch/$s_!91xa!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png\\\" data-component-name=\\\"Image2ToDOM\\\"><div class=\\\"image2-inset\\\"><picture><source type=\\\"image/webp\\\" srcset=\\\"https://substackcdn.com/image/fetch/$s_!91xa!,w_424,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 424w, https://substackcdn.com/image/fetch/$s_!91xa!,w_848,c_limit,f_webp,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0214a055-e28a-41dd-a02a-2f1f1ef26fdf_1041x968.png 848w, 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class=\\\"image-link-expand\\\"><div class=\\\"pencraft pc-display-flex pc-gap-8 pc-reset\\\"><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container restack-image\\\"><svg aria-hidden=\\\"true\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 20 20\\\" fill=\\\"none\\\" stroke-width=\\\"1.5\\\" stroke=\\\"var(--color-fg-primary)\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" xmlns=\\\"http://www.w3.org/2000/svg\\\"><g><path d=\\\"M2.53001 7.81595C3.49179 4.73911 6.43281 2.5 9.91173 2.5C13.1684 2.5 15.9537 4.46214 17.0852 7.23684L17.6179 8.67647M17.6179 8.67647L18.5002 4.26471M17.6179 8.67647L13.6473 6.91176M17.4995 12.1841C16.5378 15.2609 13.5967 17.5 10.1178 17.5C6.86118 17.5 4.07589 15.5379 2.94432 12.7632L2.41165 11.3235M2.41165 11.3235L1.5293 15.7353M2.41165 11.3235L6.38224 13.0882\\\"></path></g></svg></button><button tabindex=\\\"0\\\" type=\\\"button\\\" class=\\\"pencraft pc-reset pencraft icon-container view-image\\\"><svg xmlns=\\\"http://www.w3.org/2000/svg\\\" width=\\\"20\\\" height=\\\"20\\\" viewBox=\\\"0 0 24 24\\\" fill=\\\"none\\\" stroke=\\\"currentColor\\\" stroke-width=\\\"2\\\" stroke-linecap=\\\"round\\\" stroke-linejoin=\\\"round\\\" class=\\\"lucide lucide-maximize2 lucide-maximize-2\\\"><polyline points=\\\"15 3 21 3 21 9\\\"></polyline><polyline points=\\\"9 21 3 21 3 15\\\"></polyline><line x1=\\\"21\\\" x2=\\\"14\\\" y1=\\\"3\\\" y2=\\\"10\\\"></line><line x1=\\\"3\\\" x2=\\\"10\\\" y1=\\\"21\\\" y2=\\\"14\\\"></line></svg></button></div></div></div></a><figcaption class=\\\"image-caption\\\">aPluse status page on 2025-06-21</figcaption></figure></div><h3>Purpose</h3><ul><li><p><strong>Similarity:</strong> They are both used to set expectations.</p></li><li><p><strong>SLA</strong> is written in a way that protects the service providers\u2019 interest. That is because when the service is <a href=\\\"https://blog.alexewerlof.com/p/service-degradation-vs-disruption\\\">disrupted or degraded</a>, the service provider already looks bad. The last thing it needs is to add insult to the injury and put money on the table.</p><div class=\\\"digest-post-embed\\\" data-attrs=\\\"{&quot;nodeId&quot;:&quot;8f031692-e84a-4954-8dfc-06d2bacc50b3&quot;,&quot;caption&quot;:&quot;In the context of reliability engineering, there are three terms that are related but sometimes used incorrectly.&quot;,&quot;cta&quot;:&quot;Read full story&quot;,&quot;showBylines&quot;:true,&quot;showDescription&quot;:true,&quot;showImage&quot;:true,&quot;size&quot;:&quot;sm&quot;,&quot;isEditorNode&quot;:true,&quot;title&quot;:&quot;Degradation vs disruption&quot;,&quot;publishedBylines&quot;:[{&quot;id&quot;:87732486,&quot;name&quot;:&quot;Alex Ewerl\u00F6f&quot;,&quot;bio&quot;:&quot;Writes about technical leadership, growth mindset, and system reliability engineering.\\\\n\\\\nSenior Staff Engineer, MSc Systems Engineering from KTH, Stockholmer, dad, amateur artist.\\\\n\\\\nRead more here: https://www.alexewerlof.com/who&quot;,&quot;photo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Fe2713990-da82-481b-b579-01a7aaa5b85b_560x560.jpeg&quot;,&quot;is_guest&quot;:false,&quot;bestseller_tier&quot;:null}],&quot;post_date&quot;:&quot;2024-07-10T13:49:59.325Z&quot;,&quot;cover_image&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F0bd88583-8b9e-4ce0-8cb6-befa958a794f_943x620.png&quot;,&quot;cover_image_alt&quot;:null,&quot;canonical_url&quot;:&quot;https://blog.alexewerlof.com/p/service-degradation-vs-disruption&quot;,&quot;section_name&quot;:&quot;Reliability Engineering&quot;,&quot;video_upload_id&quot;:null,&quot;id&quot;:146395325,&quot;type&quot;:&quot;newsletter&quot;,&quot;reaction_count&quot;:18,&quot;comment_count&quot;:0,&quot;publication_id&quot;:null,&quot;publication_name&quot;:&quot;Alex Ewerl\u00F6f Notes&quot;,&quot;publication_logo_url&quot;:&quot;https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F8c58cb07-9341-402b-bcdb-9fa767c2cdac_500x500.png&quot;,&quot;belowTheFold&quot;:true,&quot;youtube_url&quot;:null,&quot;show_links&quot;:null,&quot;feed_url&quot;:null}\\\"></div></li><li><p><strong>Internal SLO</strong> is primarily used for giving a focus to service optimization.</p></li></ul><blockquote><p>\u2026 if you can\u2019t ever win a conversation about priorities by quoting a particular SLO, it\u2019s probably not worth having that SLO \u2014<a href=\\\"https://sre.google/sre-book/service-level-objectives/#id-LvQu7SYSqivIotbub-marker\\\">Google SRE book Chapter 4</a></p></blockquote><h3><strong>Revision frequency</strong></h3><ul><li><p><strong>Similarity:</strong> both are subjected to revision and readjustments as the tech evolves and/or the consumer demands changes.</p></li><li><p><strong>SLA:</strong> is revised less often and is more ceremonial because it involves business stakeholders, legal, and representatives from different parties.</p></li><li><p><strong>Internal SLO:</strong> can be revised every few months, sometimes weeks. Since its primary consumers are the internal engineers, it may go through rapid evolution to become what makes sense to them. Moreover, the internal stakeholders typically enjoy more flexibility than an external stakeholder to get what they want in a timely manner.</p></li></ul><div class=\\\"captioned-button-wrap\\\" data-attrs=\\\"{&quot;url&quot;:&quot;https://blog.alexewerlof.com/p/sla-vs-slo?utm_source=substack&utm_medium=email&utm_content=share&action=share&quot;,&quot;text&quot;:&quot;Share&quot;}\\\" data-component-name=\\\"CaptionedButtonToDOM\\\"><div class=\\\"preamble\\\"><p class=\\\"cta-caption\\\">If you find this post insightful, please share it in your circles and social media to inspire others.</p></div><p class=\\\"button-wrapper\\\" data-attrs=\\\"{&quot;url&quot;:&quot;https://blog.alexewerlof.com/p/sla-vs-slo?utm_source=substack&utm_medium=email&utm_content=share&action=share&quot;,&quot;text&quot;:&quot;Share&quot;}\\\" data-component-name=\\\"ButtonCreateButton\\\"><a class=\\\"button primary\\\" href=\\\"https://blog.alexewerlof.com/p/sla-vs-slo?utm_source=substack&utm_medium=email&utm_content=share&action=share\\\"><span>Share</span></a></p></div><div><hr></div><p><em><a href=\\\"https://blog.alexewerlof.com/p/faq#%C2%A7payment\\\">My monetization strategy</a> is to give away most content for free. These posts take anywhere from a few hours to a few days to draft, edit, research, illustrate, and publish. I pull these hours from my private time, vacation days and weekends. The simplest way to support this work is to <strong>like</strong>, <strong>subscribe</strong> and <strong>share</strong> it. If you really want to support me lifting our community, you can consider a paid subscription. If you want to save money, you can get 20% off via <a href=\\\"https://blog.alexewerlof.com/protipsdiscount\\\">this link</a>. As a token of appreciation, subscribers get full access to the Pro-Tips sections and my online book <a href=\\\"https://blog.alexewerlof.com/p/rem\\\">Reliability Engineering Mindset</a>. Your contribution also funds my open-source products like <a href=\\\"https://slc.alexewerlof.com/\\\">Service Level Calculator</a>. You can also <a href=\\\"https://blog.alexewerlof.com/leaderboard\\\">invite your friends</a> to gain free access.</em></p><p><em>And to those of you who support me already, <strong>thank you</strong> for sponsoring this content for the others. \uD83D\uDE4C If you have questions or feedback, or you want me to dig deeper into something, please let me know in the comments.</em></p>\",\"has_dynamic_content\":false,\"truncated_body_text\":\"\u201CI want all teams to set SLAs between each other\u201D, said the leadership.\",\"wordcount\":2295,\"post_preview_limit\":null,\"language\":\"en\",\"postTags\":[{\"id\":\"2a106382-e2d8-4cf8-a7b3-753207bef109\",\"publication_id\":1002265,\"name\":\"non-functional requirements\",\"slug\":\"non-functional-requirements\",\"hidden\":false},{\"id\":\"4010aeb1-ad54-4c2f-85dc-901526c78867\",\"publication_id\":1002265,\"name\":\"sli\",\"slug\":\"sli\",\"hidden\":false},{\"id\":\"534a54d4-65f3-4e24-88c0-c603442c7530\",\"publication_id\":1002265,\"name\":\"slo\",\"slug\":\"slo\",\"hidden\":false},{\"id\":\"5b282f58-1b12-4376-8f35-cbe4f8e29034\",\"publication_id\":1002265,\"name\":\"business\",\"slug\":\"business\",\"hidden\":false},{\"id\":\"708c5d41-9dd6-49e4-a489-8e33d501043a\",\"publication_id\":1002265,\"name\":\"business capabilities\",\"slug\":\"business-capabilities\",\"hidden\":false},{\"id\":\"87c5b84b-5744-4550-b6ae-3b0a3b224e70\",\"publication_id\":1002265,\"name\":\"service design\",\"slug\":\"service-design\",\"hidden\":false},{\"id\":\"8daae20f-49fb-4b42-a6a2-2e1a3563dc98\",\"publication_id\":1002265,\"name\":\"sre\",\"slug\":\"sre\",\"hidden\":false},{\"id\":\"ae2bf941-bf61-45c2-a8b9-a6dc27247c3a\",\"publication_id\":1002265,\"name\":\"service levels\",\"slug\":\"service-levels\",\"hidden\":false},{\"id\":\"c0a6497c-b041-4bf5-88cd-f682a9273f5f\",\"publication_id\":1002265,\"name\":\"sla\",\"slug\":\"sla\",\"hidden\":false},{\"id\":\"c1909669-f9f0-4ce5-93d9-8e583e798875\",\"publication_id\":1002265,\"name\":\"availability\",\"slug\":\"availability\",\"hidden\":false}],\"postCountryBlocks\":[],\"headlineTest\":null,\"coverImagePalette\":{\"Vibrant\":{\"rgb\":[251,187,84],\"population\":62},\"DarkVibrant\":{\"rgb\":[12,82,54],\"population\":79},\"LightVibrant\":{\"rgb\":[252,100,100],\"population\":104},\"Muted\":{\"rgb\":[100,140,164],\"population\":1},\"DarkMuted\":{\"rgb\":[75,44,57],\"population\":12},\"LightMuted\":{\"rgb\":[150.09493670886076,2.9050632911392276,2.9050632911392276],\"population\":0}},\"publishedBylines\":[{\"id\":87732486,\"name\":\"Alex Ewerl\u00F6f\",\"handle\":\"alexewerlof\",\"photo_url\":\"https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Fe2713990-da82-481b-b579-01a7aaa5b85b_560x560.jpeg\",\"bio\":\"Writes about technical leadership, growth mindset, and system reliability engineering. 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It seemed like it fit the definition of an SLA in principle, but not a legal agreement as defined by this article. In fact, you referenced one of the consequences we used- no features deployed until x,y,z. In which of these acronyms would you classify that? Ok to use SLA? Or is the legal part strict?\",\"body_json\":{\"type\":\"doc\",\"attrs\":{\"schemaVersion\":\"v1\"},\"content\":[{\"type\":\"paragraph\",\"content\":[{\"type\":\"text\",\"text\":\"I\u2019ve had teams set agreements with each other that specify the consequences if the error budget is depleted. It seemed like it fit the definition of an SLA in principle, but not a legal agreement as defined by this article. In fact, you referenced one of the consequences we used- no features deployed until x,y,z. In which of these acronyms would you classify that? Ok to use SLA? 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