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Difficulty: MediumHigh Availability and Disaster Recovery Design

A digital advertising company is designing a real-time bidding platform. The application tier runs on Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer (ALB) across multiple Availability Zones in a primary AWS Region. The database tier uses an Amazon Aurora PostgreSQL DB cluster. The company requires a multi-region disaster recovery (DR) strategy in a secondary AWS Region. The design must support a Recovery Time Objective (RTO) of less than 1010 minutes and a Recovery Point Objective (RPO) of less than 11 minute while minimizing cost. Which architecture meets these requirements?

  1. Deploy an Amazon Aurora Global Database with the primary cluster in the primary region and a secondary cluster in the secondary region. Deploy a minimum-capacity Auto Scaling group and an ALB in the secondary region. Configure Amazon Route 53 failover routing records pointing to the ALBs in both regions, and associate the primary record with a Route 53 health check that monitors the primary application endpoint.Answer
  2. B
    Deploy an Amazon Aurora Global Database with the primary cluster in the primary region and a secondary cluster in the secondary region. Deploy a minimum-capacity Auto Scaling group and an ALB in the secondary region. Configure Amazon Route 53 failover routing records pointing to the ALBs in both regions, but do not associate the primary record with an application health check to avoid false failovers.
  3. C
    Configure daily Amazon Aurora database backups and copy the snapshots to the secondary region. Use an AWS CloudFormation template to deploy the ALB, Auto Scaling group, and Aurora PostgreSQL database in the secondary region only when a disaster is declared, and update Route 53 records manually.
  4. D
    Deploy an Amazon Aurora PostgreSQL DB cluster in Multi-AZ mode in the primary region. Create an Aurora Read Replica in the secondary region, and configure Aurora Auto Scaling on the secondary replica to automatically accept write traffic if the primary region fails. Configure Route 53 latency-based routing to distribute traffic between the regions.

Answer

Deploying an Amazon Aurora Global Database with a warm standby application tier in the secondary region, combined with Amazon Route 53 failover routing and health checks, meets both the RTO and RPO requirements at a lower cost than an active-active multi-region setup.
The correct answer proposes an Amazon Aurora Global Database for sub-second database replication, satisfying the RPO of less than 11 minute. By maintaining a minimum-capacity Auto Scaling group in the secondary region (Warm Standby), costs are minimized compared to active-active, while still allowing the application to scale up within the 1010-minute RTO. Route 53 failover routing with an associated health check ensures that traffic is automatically redirected to the secondary region if the primary region's application becomes degraded.

Step-by-Step Solution

1
Select a database replication technology that meets the RPO constraint.
Amazon Aurora Global Database provides sub-second replication latency to a secondary region, which satisfies the RPO of less than 11 minute.
Standard database snapshots or cross-region read replicas without proper failover mechanisms will not satisfy the strict recovery objectives.
2
Select a disaster recovery pattern for the application tier that meets the RTO constraint.
A warm standby pattern with a minimum-capacity Auto Scaling group in the secondary region allows for rapid scaling to handle production traffic within 1010 minutes.
Rebuilding the infrastructure using CloudFormation from scratch takes too long and exceeds the 1010-minute RTO.
3
Configure DNS routing and health checks for automated failover.
Create Route 53 failover routing records and associate the primary record with a health check monitoring the primary application's availability.
Without Route 53 health checks, the DNS failover cannot be automated, leaving the system vulnerable to prolonged downtime during an outage.

Key Concept

Disaster Recovery Patterns and DNS Failover Design
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Topics

High Availability and Disaster Recovery Design

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