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Difficulty: EasyHigh Availability and Disaster Recovery Design

A company is designing a disaster recovery strategy for a non-critical internal reporting application. The business requirements specify a Recovery Time Objective (RTO) of 24 hours and a Recovery Point Objective (RPO) of 24 hours. The primary objective is to minimize ongoing infrastructure running costs in the secondary region. Which disaster recovery strategy should the solutions architect recommend to meet these requirements?

  1. Backup and Restore, copying EBS snapshots and database backups to the secondary region and provisioning resources only during a failover eventAnswer
  2. B
    Pilot Light, keeping a minimal version of the application stack running and replicating database transactions to a small standby database in the secondary region
  3. C
    Warm Standby, deploying a scaled-down but fully functional version of the environment in the secondary region that is ready to scale up immediately
  4. D
    Multi-Site Active-Active, running fully scaled duplicate environments in both regions and routing traffic using Route 53 latency-based routing

Answer

Backup and Restore, copying EBS snapshots and database backups to the secondary region and provisioning resources only during a failover event
The correct answer is the strategy that copies backups and snapshots to the destination region and only provisions compute and database resources when a disaster is declared. This meets the 24-hour RTO and RPO requirements with the lowest possible cost because no active AWS infrastructure (like EC2 or RDS instances) is running in the disaster recovery region during normal operations.

Step-by-Step Solution

1
Analyze the RTO and RPO requirements of 24 hours.
A 24-hour window is sufficient to restore databases from backups and provision virtual machines using automated scripts and AMIs.
Understanding the time limit determines if resources must be pre-warmed or if they can be created on-demand during a disaster.
2
Evaluate the cost constraint (minimize ongoing infrastructure running costs).
The target strategy must avoid keeping running compute or database instances in the secondary region during normal operations.
Running inactive standby instances increases monthly costs, which violates the cost optimization constraint.
3
Select the disaster recovery strategy that matches both constraints.
Backup and Restore only incurs storage costs for backups and snapshots in the secondary region, provisioning compute and database capacity only during failover.
Backup and Restore satisfies the 24-hour RTO and RPO while ensuring the lowest baseline operational cost.

Key Concept

Disaster Recovery strategies cost and RTO/RPO trade-offs
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Topics

High Availability and Disaster Recovery Design

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