Microsoft Certified: DevOps Engineer ExpertImplement a Site Reliability Engineering (SRE) strategyMedium
A company is implementing a disaster recovery strategy for its critical application hosted on Azure. The application uses Azure App Service for its front end and Azure SQL Database for its data store. The RTO (Recovery Time Objective) is 4 hours, and the RPO (Recovery Point Objective) is 1 hour. The company wants to minimize costs while meeting these objectives. Which disaster recovery strategy should they implement?
- AWarm Standby
- BBackup and Restore
- CHot Standby (Active-Active)
- DPilot Light
Show answer & explanationAnswer & explanation
Correct answer: A. Warm Standby
A Warm Standby strategy involves having a scaled-down but functional copy of the environment in a secondary region. This allows for faster recovery than Backup and Restore or Pilot Light, making it suitable for an RTO of 4 hours. Azure SQL Database's geo-replication can meet the 1-hour RPO. It's also more cost-effective than a full Hot Standby.
Why the other options are wrong
- B. Backup and Restore typically has a much higher RTO (many hours to days) and RPO (hours to days), making it unsuitable for the given 4-hour RTO and 1-hour RPO.
- C. Hot Standby (Active-Active) would meet the RTO/RPO but is the most expensive option, and the question specifies minimizing costs while meeting objectives, making Warm Standby a better fit.
- D. Pilot Light involves deploying core infrastructure and data, but requires significant spin-up time for compute resources, likely exceeding a 4-hour RTO.
Warm Standby DR
A disaster recovery strategy where a scaled-down, but fully functional, duplicate environment is maintained in a secondary region, ready to be scaled up and take over production traffic.
- Balances RTO/RPO with cost.
- Faster recovery than Pilot Light or Backup & Restore.
- Requires continuous replication of data.
Memory trick: Recovering from disaster, each strategy offers a different speed and price.