Disaster Recovery Strategies for AWS

Disaster Recovery (DR) is not just about backups; it's about business continuity. On AWS, you have multiple strategies, each with a different trade-off between cost and recovery time.

Understand RTO and RPO

• Recovery Time Objective (RTO): How quickly do you need to be back online after a disaster? (e.g., 15 minutes, 4 hours).
• Recovery Point Objective (RPO): How much data can you afford to lose? (e.g., 5 minutes of data, 24 hours of data).

The Four DR Strategies

1. Backup and Restore (Highest RTO/RPO): The cheapest and simplest. Regularly back up your data (e.g., RDS snapshots, EBS snapshots) to S3 in another region. Recovery is manual and can take hours.
2. Pilot Light: A small, core part of your infrastructure is always running in the DR region (e.g., a replicated database). In a disaster, you scale up the application servers around it. Faster than Backup/Restore.
3. Warm Standby: A scaled-down but fully functional version of your application is always running in the DR region. Failover is faster as you only need to scale up and redirect traffic via DNS (like Amazon Route 53).
4. Multi-Site Active-Active (Lowest RTO/RPO): The most expensive and complex. You run your full application in multiple regions simultaneously, distributing traffic between them. If one region fails, traffic is automatically routed to the healthy regions. This provides near-zero downtime.