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

A global supply chain logistics platform hosts its fleet scheduling system in the us-east-1 Region. The architecture consists of Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer, and a primary Amazon Aurora PostgreSQL database cluster. The company needs to design a disaster recovery (DR) solution in the us-west-2 Region. The DR solution must achieve a Recovery Time Objective (RTO) of 20 minutes and a Recovery Point Objective (RPO) of 5 minutes while minimizing ongoing running costs. Which two steps should the solutions architect take to meet these requirements?

  1. Set up an Amazon Aurora Global Database with the primary cluster in the primary Region and a secondary cluster in the disaster recovery Region.Answer
  2. Deploy an Auto Scaling group in the disaster recovery Region with the minimum and desired capacity set to 0, and use a script or AWS CloudFormation to scale out the instances during a failover.Answer
  3. C
    Deploy an Amazon RDS PostgreSQL Read Replica in the disaster recovery Region, and configure the primary Application Load Balancer to automatically route write transactions to the read replica if the primary database becomes unavailable.
  4. D
    Establish a Warm Standby DR solution by running a fully duplicated, active Auto Scaling group with the same instance counts in both Regions and utilizing Route 53 Latency routing.
  5. E
    Perform daily database backups to Amazon S3, transition the backups to S3 Glacier Flexible Retrieval, and restore the database to a new instance in the disaster recovery Region during a failover event.

Answer

Configure an Amazon Aurora Global Database with a secondary cluster in the recovery Region, and deploy an Auto Scaling group in the recovery Region with its capacity initialized to 0, scaling it out on-demand during failover.
The correct solution uses a Pilot Light disaster recovery strategy. Setting up an Aurora Global Database ensures asynchronous, sub-second replication to the secondary Region, keeping the database in sync and satisfying the 5-minute RPO. Deploying an Auto Scaling group with minimum and desired capacity set to 0 avoids active compute charges during normal operations, which satisfies the cost minimization constraint. In the event of a disaster, the database can be promoted quickly, and the Auto Scaling group can be scaled out via automation within the 20-minute RTO.

Step-by-Step Solution

1
Analyze the RTO and RPO requirements alongside the cost minimization constraint.
The RPO of 5 minutes requires active database replication to the secondary Region. The RTO of 20 minutes allows the application tier to be scaled down to zero and started on demand (Pilot Light).
The architecture needs to support fast recovery but avoid the cost of active compute in the recovery Region.
2
Address the database layer requirements.
Set up an Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2.
Aurora Global Database provides sub-second latency replication, meeting the RPO of 5 minutes, and supports sub-minute failovers to meet the RTO.
3
Address the compute layer requirements.
Deploy an Auto Scaling group in us-west-2 with minimum and desired capacity set to 0. Use a template or script to scale out compute during failover.
This Pilot Light strategy avoids compute charges in the DR Region during normal operations, satisfying the cost-minimization constraint while allowing instance provisioning within the 20-minute RTO.

Key Concept

Disaster Recovery strategies (specifically Pilot Light) and cross-region replication technologies.
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Topics

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

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