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

An enterprise runs a critical payroll application on AWS in the `us-east-1` Region. The application uses Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB), with an Amazon RDS for PostgreSQL DB instance. The company must design a disaster recovery (DR) strategy in the `us-west-2` Region to protect against a regional outage. The solution must achieve a Recovery Point Objective (RPO) of 55 minutes and a Recovery Time Objective (RTO) of 1010 minutes while minimizing ongoing running costs. Which strategy should a solutions architect recommend to meet these requirements?

  1. A
    Deploy the EC2 instances and ALB in the secondary Region via AWS CloudFormation, but keep the EC2 instances in a stopped state. Create a cross-region read replica of the RDS DB instance. In the event of a disaster, start the EC2 instances, promote the read replica to primary, and update the DNS records in Route 53.
  2. B
    Enable Multi-AZ deployment on the RDS DB instance, selecting the secondary Region as the standby Availability Zone. Deploy the EC2 instances behind an ALB in the secondary Region. Configure Route 53 to automatically route traffic to the standby DB instance if the primary DB instance in the primary Region becomes unavailable.
  3. Deploy a scaled-down Auto Scaling group of EC2 instances behind an ALB in the secondary Region, and create a cross-region read replica of the RDS DB instance. Configure Amazon Route 53 failover routing with health checks. In the event of a disaster, promote the replica to primary, scale out the EC2 instances, and allow Route 53 to redirect traffic.Cevap
  4. D
    Deploy a scaled-down Auto Scaling group of EC2 instances behind an ALB in the secondary Region, and create a cross-region read replica of the RDS DB instance. Configure Amazon Route 53 with a latency routing policy to distribute traffic between the two Regions. In the event of a disaster, promote the read replica to primary.

Cevap

Deploy a scaled-down Auto Scaling group of EC2 instances behind an ALB in the secondary Region, create a cross-region read replica of the RDS DB instance, configure Amazon Route 53 failover routing with health checks, and in a disaster, promote the replica and scale out the compute resources.
The correct strategy is a Warm Standby DR pattern. Deploying a scaled-down but active compute tier in the secondary region ensures that instances are already running and registered with the ALB. In a disaster, the solutions architect only needs to promote the RDS cross-region read replica (which handles the database replication with under 55 minutes of lag to satisfy the RPO) and scale out the EC2 Auto Scaling group. Route 53 failover routing with health checks automatically detects the primary region failure and reroutes traffic, completing the recovery well within the 1010-minute RTO.

Adım Adım Çözüm

1
Evaluate the RPO requirement of 55 minutes.
Amazon RDS cross-region read replicas replicate asynchronously with very low latency (typically seconds or minutes), satisfying the 55-minute RPO constraint.
Standard backup restoration from snapshots copied across regions fails the RPO constraint as backups are usually taken daily.
2
Evaluate the RTO requirement of 1010 minutes.
A Warm Standby pattern is selected. Scaled-down but running EC2 instances are kept active in the secondary Region, ready to scale out immediately.
A Pilot Light strategy with stopped instances or deploying resources purely from CloudFormation templates during a disaster cannot guarantee recovery and initialization within 1010 minutes.
3
Design the failover routing mechanism using Route 53.
A failover routing policy combined with health checks is configured to dynamically redirect client traffic to the secondary ALB when the primary region becomes unhealthy.
Using latency routing without health checks will not redirect traffic away from the failed primary region.

Anahtar Kavram

Disaster Recovery strategies (Warm Standby vs. Pilot Light) and Cross-Region DB Replication
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Konular

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

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