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Difficulty: MediumMulti-AZ, Multi-Region Architectures and Disaster Recovery (DR)

A digital media publishing company hosts its content management system (CMS) on AWS. The application tier runs on Amazon EC2 instances in an Auto Scaling group, and the database tier uses an Amazon RDS for PostgreSQL DB instance in a Multi-AZ deployment. The company wants to establish a disaster recovery (DR) strategy in a secondary AWS Region with a Recovery Time Objective (RTO) of 20 minutes and a Recovery Point Objective (RPO) of 10 minutes. The strategy must also minimize ongoing running costs. Which two actions should the solutions architect take to meet these requirements? (Select TWO.)

  1. Configure an Amazon RDS Cross-Region Read Replica in the secondary Region, and promote it to a standalone primary database instance during a failover event.Answer
  2. Deploy a scaled-down application tier in the secondary Region, and configure Amazon Route 53 with a failover routing policy to redirect traffic during a failover event.Answer
  3. C
    Configure Amazon RDS Multi-AZ replication to synchronously replicate data to a standby instance in the secondary Region to ensure automated database failover.
  4. D
    Back up the database daily to Amazon S3, replicate the backups to the secondary Region, and use an Amazon S3 Glacier Flexible Retrieval lifecycle policy to archive them to minimize storage costs.
  5. E
    Configure Amazon Route 53 with a latency routing policy to automatically route all user traffic to the secondary Region when the primary database is offline.

Answer

Configure an Amazon RDS Cross-Region Read Replica in the secondary Region to meet the RPO, and deploy a scaled-down application tier in the secondary Region with Amazon Route 53 failover routing to meet the RTO while minimizing costs.
The combination of configuring an Amazon RDS Cross-Region Read Replica and deploying a scaled-down application tier in the secondary region with Route 53 failover routing satisfies both recovery objectives. The cross-region read replica replicates database changes asynchronously, ensuring the RPO of 10 minutes is met, and can be promoted to primary during failover. The scaled-down application tier maintains a small footprint to minimize ongoing costs, but can scale up rapidly to meet the 20-minute RTO, while Route 53 handles the redirection of client traffic.

Step-by-Step Solution

1
Analyze the database replication options that satisfy a cross-region RPO of 10 minutes.
RDS Cross-Region Read Replicas replicate data asynchronously with typical lag times of seconds, satisfying the 10-minute RPO. Multi-AZ replication cannot span across regions, and daily backups would fail the RPO.
To identify database configurations capable of keeping data synchronized across regions within the recovery point limit.
2
Evaluate the recovery strategy for the application tier to meet the 20-minute RTO while minimizing running costs.
A scaled-down application tier in the standby region (Warm Standby) minimizes idle resource costs while allowing the instances to be quickly scaled up to handle the production workload within the 20-minute window.
To select the application recovery tier strategy that satisfies the time objective and cost constraints.
3
Determine the routing mechanism required to redirect client requests to the secondary region during a disaster.
Amazon Route 53 failover routing policy combined with health checks automatically detects primary region degradation and switches DNS resolution to the standby region. Latency routing does not provide this active-passive behavior.
To orchestrate automated, high-availability DNS redirection to the recovery region.

Key Concept

Disaster recovery (DR) planning requires balancing cost, Recovery Time Objective (RTO), and Recovery Point Objective (RPO). For multi-region recovery, RDS Cross-Region Read Replicas provide low RPO by replicating asynchronously. A Warm Standby deployment pattern (scaled-down active resources) combined with Route 53 failover routing achieves low RTO while minimizing running costs compared to a fully duplicated environment.

Alternative Method

For databases with extremely low RTO and RPO requirements (e.g., RPO near zero, RTO under 1 minute), migrating from RDS PostgreSQL to Amazon Aurora Global Database would be a more performant alternative, though it might increase operational complexity and database licensing costs.
Estimated Time:2m 0s
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Topics

Multi-AZ, Multi-Region Architectures and Disaster Recovery (DR)

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