AWS Certified Solutions Architect – Associate (SAA-C03)Design Resilient ArchitecturesHard
A global e-commerce company operates a mission-critical application with a multi-tier architecture in the `us-east-1` region. They need to implement a disaster recovery (DR) strategy that minimizes costs while providing a recovery time objective (RTO) of less than 4 hours and a recovery point objective (RPO) of less than 1 hour. This strategy should involve having a minimal, but ready-to-scale, environment in a secondary region. Which disaster recovery strategy should they choose?
- ABackup and Restore
- BMulti-site Active/Active
- CWarm Standby
- DPilot Light
Show answer & explanationAnswer & explanation
Correct answer: D. Pilot Light
The Pilot Light strategy involves keeping a minimal set of core resources running in the DR region (e.g., database, DNS) and scaling up the remaining application components when a disaster occurs. This meets the RTO of less than 4 hours and RPO of less than 1 hour, balancing cost minimization with recovery speed effectively.
Why the other options are wrong
- A. Backup and Restore has a high RTO (hours to days) and RPO (hours), which is too slow for the given requirements.
- B. Multi-site Active/Active offers the lowest RTO and RPO (near zero) but is the most expensive strategy, as full environments run in multiple regions.
- C. Warm Standby has a lower RTO (minutes) and RPO (seconds/minutes) than Pilot Light but is more expensive as more resources are continuously running.
Pilot Light DR Strategy
A disaster recovery strategy where a small, minimal copy of an application's core infrastructure is continuously running in a secondary region. In a disaster, this 'pilot light' environment is scaled up to full production capacity.
- Cost-effective (minimal running resources)
- RTO: tens of minutes to a few hours
- RPO: minutes
- Good balance of cost and recovery speed
- Core services like databases are replicated/running
Memory trick: Pilot Light: a small 'spark' ready to ignite.