A company is implementing an SRE strategy for its mission-critical application hosted on Azure. The application's data is stored in Azure Cosmos DB. The team needs to design a disaster recovery strategy that ensures database consistency and minimal data loss across two separate Azure regions, with an RPO (Recovery Point Objective) as close to zero as possible. Which Cosmos DB feature should they leverage?
- AContinuous Backup with Point-in-Time Restore.
- BMulti-region writes with Strong consistency.
- CAnalytical Store with Synapse Link.
- DMulti-region reads with Session consistency.
Show answer & explanationAnswer & explanation
Correct answer: B. Multi-region writes with Strong consistency.
An RPO 'as close to zero as possible' for a mission-critical application demanding 'database consistency' across 'two separate Azure regions' points directly to multi-region writes with Strong consistency in Azure Cosmos DB. This configuration ensures that all writes are synchronously committed to all configured regions before being acknowledged, providing the highest level of data consistency and near-zero RPO, albeit with potential write latency implications. Other options do not meet the strict RPO and consistency requirements across regions.
Why the other options are wrong
- A. Continuous Backup with Point-in-Time Restore provides an RPO of minutes (up to 5 minutes) and is for single-region recovery or geo-restore, not cross-region active data consistency with near-zero RPO.
- C. Analytical Store is for analytical workloads and Synapse Link for ETL, not for real-time transactional data consistency and disaster recovery with near-zero RPO.
- D. Multi-region reads with Session consistency allows for lower latency reads but does not guarantee strong consistency across regions or near-zero RPO for writes, as writes are still asynchronously replicated or may have eventual consistency guarantees.
Cosmos DB Multi-Region Writes (Strong Consistency)
A configuration in Azure Cosmos DB where a database account is deployed across multiple Azure regions, allowing write operations to be performed in any region. When combined with Strong consistency, writes are synchronously committed to all regions before acknowledgment, ensuring near-zero RPO.
- Provides global distribution with highest consistency guarantees.
- Achieves RPO as close to zero as possible.
- Writes are synchronous across all regions.
- May introduce higher write latency due to cross-region synchronization.
Memory trick: Cosmos DB RPO: 'Multi-region writes, strong consistency, zero tears.'