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## **1. Objective**

Ensure business continuity and data protection by implementing an effective DR strategy for the customer, leveraging EFS replication, RDS PITR, and different failover methods.

## **2. DR Scenarios & Recovery Options**

|                    | **Method**                      | **RDS Recovery** | **EFS Recovery**             | **Failover Steps**                                                                                | **Estimated Downtime (RTO)** | **RPO** | **Cost Impact** |
| ------------------ | ------------------------------- | ---------------- | ---------------------------- | ------------------------------------------------------------------------------------------------- | ---------------------------- | ------- | --------------- |
| DR Basic Service   | **Cold Backup-Restore**         | Snapshot (6h)    | Backup Restore (6h)          | 1. Restore RDS from snapshot (6h)  <br>2. Restore EFS from snapshot (6h)  <br>3. Recover EKS (4h) | **24 hours**                 | 4 hours | **Base Cost**   |
| DR Premium Service | **EFS Replica Only (RDS PITR)** | PITR (6h)        | EFS Replica + Restore (0.2h) | 1. RDS recovery from PITR (6h)  <br>2. Stop EFS sync (0.2h)  <br>3. Full EKS recovery             | **6 hours**                  | 15 min  | **+30% Cost**   |

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## **3. Downtime Estimation & RTO Considerations**

- **EFS Replica Only (RDS PITR)**
    - **6-hour RTO**, significantly reducing downtime compared to cold restore.
    - **15-minute RPO** ensures minimal data loss.

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## **4. DR Execution Plan**

### **4.1 Pre-DR Readiness Checks**

- Ensure **EFS replication** is active and functioning correctly.
- Verify **RDS PITR backups** and retention policies.
- Pre-configure **EKS deployment templates(Velero)** for rapid recovery.

### **4.2 Disaster Recovery Trigger**

- DR activation is **initiated upon a major failure event** in the primary environment.
- Decision criteria include **regional failure, prolonged service outage, or severe data corruption**.

### **4.3 Execution Steps**

#### **EFS Replica Only (RDS PITR)**

1. **Recover RDS** from PITR (**6 hours**).
2. **Stop EFS replication sync** (**0.2 hours**).
3. **Recover EKS cluster** and validate application (**immediate**).

### **4.4 Post-Failover Validation**

- Confirm **data consistency** between DR and primary environments.
- Validate **application services and connectivity**.
- Communicate DR activation and service restoration to stakeholders.

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## **5. DR Testing & Cost Estimation**

- **Annual DR validation test** is required, adding an **estimated 2 months of AWS costs**.
    - **EFS Replica Only (RDS PITR):**
        - **$20.8K/month** 

