A company runs a critical web application on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB) in the us-east-1 Region. The application uses an Amazon RDS for PostgreSQL database for stateful data and an Amazon S3 bucket to store static user uploads. A SysOps Administrator must establish a disaster recovery (DR) strategy in the us-west-2 Region. The strategy must achieve a Recovery Point Objective (RPO) of 15 minutes and a Recovery Time Objective (RTO) of 30 minutes while minimizing costs during normal operations. Which setup meets these requirements?
- Configure an RDS cross-region read replica in us-west-2. Enable versioning on both the source and destination S3 buckets, and configure S3 Cross-Region Replication (CRR) to us-west-2. In us-west-2, deploy an ALB and an Auto Scaling group with the desired capacity set to 0. Create Amazon Route 53 Active-Passive failover records with health checks pointing to the us-east-1 ALB.Answer
- BConfigure the Amazon RDS database as a Multi-AZ deployment with the standby replica located in us-west-2. Configure S3 Cross-Region Replication (CRR) to us-west-2. In us-west-2, deploy an ALB and an Auto Scaling group with the desired capacity set to 0. Create Amazon Route 53 Active-Passive failover records.
- CConfigure an RDS cross-region read replica in us-west-2. Configure S3 Cross-Region Replication (CRR) from the source bucket to a destination bucket in us-west-2 without enabling S3 versioning. In us-west-2, deploy an ALB and an Auto Scaling group with the desired capacity set to 0. Create Amazon Route 53 Active-Passive failover records.
- DConfigure an RDS cross-region read replica in us-west-2. Enable versioning on both S3 buckets and configure S3 Cross-Region Replication (CRR) to us-west-2. In us-west-2, deploy an ALB and an Auto Scaling group with the desired capacity matching the primary region. Configure Amazon Route 53 active-active Weighted routing records with equal weight (50/50) to balance traffic across both regions during normal operations.
Answer
Configure an RDS cross-region read replica in us-west-2. Enable versioning on both the source and destination S3 buckets, and configure S3 Cross-Region Replication (CRR) to us-west-2. In us-west-2, deploy an ALB and an Auto Scaling group with the desired capacity set to 0. Create Amazon Route 53 Active-Passive failover records with health checks pointing to the us-east-1 ALB.
The correct solution represents a classic Pilot Light disaster recovery strategy. Creating an Amazon RDS cross-region read replica provides asynchronous replication that keeps data updated within seconds, meeting the 15-minute RPO requirement. S3 Cross-Region Replication (CRR) satisfies the S3 RPO requirement, but it strictly requires versioning to be enabled on both the source and destination S3 buckets. To minimize running costs during normal operations, the Auto Scaling group in the recovery region is scaled to 0. During a disaster, the read replica is promoted to a standalone database and the Auto Scaling group is scaled up to handle traffic routed by Route 53 failover routing, all of which can be completed well within the 30-minute RTO.
Step-by-Step Solution
Key Concept
Implementing a cost-effective Pilot Light Disaster Recovery strategy using RDS cross-region replication, S3 Cross-Region Replication with versioning, and zero-capacity Auto Scaling groups.
Estimated Time:3m 0s