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

A financial subscription billing application runs on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer in the us-east-1 Region. The application database is hosted on an Amazon RDS for PostgreSQL DB instance. The company wants to implement a disaster recovery (DR) strategy in the us-west-2 Region with a Recovery Time Objective (RTO) of less than 15 minutes and a Recovery Point Objective (RPO) of less than 5 minutes. The solution must minimize running costs under normal conditions. Which combination of actions should a solutions architect recommend to meet these requirements? (Select TWO.)

  1. Create an Amazon RDS for PostgreSQL cross-region read replica in the secondary region, and promote it to a standalone DB instance during a failover event.Answer
  2. Deploy an Application Load Balancer and a scaled-down Auto Scaling group of EC2 instances in the secondary region, and configure the group to scale up when a failover is initiated.Answer
  3. C
    Enable Multi-AZ deployment for the RDS DB instance with a standby replica located in the secondary region to provide automatic, synchronous failover.
  4. D
    Use Amazon Route 53 latency routing to automatically redirect client requests to the secondary region during an outage without attaching health checks.
  5. E
    Store database transaction logs in an Amazon S3 Glacier Flexible Retrieval vault in the secondary region, and use expedited retrievals to restore the database during a failover.

Answer

To achieve the required RTO of under 15 minutes and RPO of under 5 minutes cost-effectively, configure an Amazon RDS cross-region read replica for database replication and deploy a scaled-down Auto Scaling group behind an Application Load Balancer in the secondary region to scale up during failover.
The correct strategy combines database replication and scaled-down compute resources. An RDS cross-region read replica maintains a replica of the database with sub-minute lag (RPO) and can be promoted to primary in minutes (RTO). A scaled-down Auto Scaling group in the secondary region acts as a Warm Standby, minimizing costs during normal operations while guaranteeing that application instances can scale up quickly during a disaster to meet the RTO.

Step-by-Step Solution

1
Address the database RPO and RTO constraints.
Deploy an Amazon RDS cross-region read replica.
Asynchronous cross-region replication keeps replication lag (RPO) within seconds. Promoting the read replica to a standalone primary database can be completed in a few minutes, meeting the 15-minute RTO.
2
Address the compute RTO and cost constraints.
Implement a Warm Standby pattern with a scaled-down Auto Scaling group and an Application Load Balancer in the disaster recovery region.
Maintaining a minimal number of running EC2 instances keeps idle costs low while ensuring the system can quickly scale up to production capacity, meeting the 15-minute RTO.

Key Concept

Cross-region disaster recovery strategies involving database replication and pre-provisioned scaled-down application infrastructure to meet specific RTO/RPO limits.
Estimated Time:2m 0s
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Topics

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

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