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Difficulty: MediumHigh Availability and Disaster Recovery Design

A pharmaceutical company is designing a new regulatory compliance document management system. The primary deployment will run in the us-east-1 Region. The system consists of an application tier hosted on Amazon EC2 instances in private subnets behind an Application Load Balancer (ALB), and a database tier using Amazon Aurora PostgreSQL. The company requires a multi-region disaster recovery (DR) architecture between us-east-1 and us-west-2. The solution must achieve a Recovery Time Objective (RTO) of 30 minutes, a Recovery Point Objective (RPO) of 5 minutes, and minimize ongoing running costs in the secondary region.

Which two actions should a solutions architect take to meet these requirements?

  1. Set up an Amazon Aurora Global Database with the primary database cluster in us-east-1 and a secondary database cluster in us-west-2.Answer
  2. Create an Auto Scaling group for the application tier in us-west-2 with the desired capacity set to 0, and configure a failover routing policy in Amazon Route 53 that points to the ALBs in both regions.Answer
  3. C
    Configure an Amazon RDS PostgreSQL Read Replica in us-west-2 and use Amazon Route 53 Application Recovery Controller (ARC) to automate synchronous replication failover.
  4. D
    Configure a Route 53 failover routing policy pointing to both ALBs, but disable health checks on the primary record in us-east-1 to prevent accidental failover during brief latency spikes.
  5. E
    Configure the route tables of the private subnets in us-west-2 to route outbound internet traffic through an AWS Transit Gateway peering connection attached to a NAT Gateway in us-east-1.

Answer

Setting up an Amazon Aurora Global Database with the primary cluster in us-east-1 and a secondary cluster in us-west-2, combined with creating an Auto Scaling group in us-west-2 with the desired capacity set to 0 and configuring Route 53 failover routing.
The correct answer combines Amazon Aurora Global Database for near-instant database replication and a cost-effective Pilot Light compute tier using an Auto Scaling group set to 0 capacity in the secondary region. Aurora Global Database ensures the RPO is well under 5 minutes by replicating data asynchronously with sub-second lag, and it can be promoted to a primary cluster within minutes. Keeping the EC2 instances in the secondary region turned off (desired capacity of 0) minimizes running costs, while allowing them to scale up and start serving traffic within the 30-minute RTO window when Route 53 failover is triggered.

Step-by-Step Solution

1
Select a database replication strategy that satisfies the RPO of 5 minutes.
Amazon Aurora Global Database provides database replication that completes in less than 1 second, meeting the RPO of 5 minutes.
Ensures that minimal data is lost during a regional failover.
2
Select a compute strategy that minimizes ongoing costs while meeting the RTO of 30 minutes.
Pre-configuring the Auto Scaling group in the recovery region (us-west-2) with a desired capacity of 0 ensures no EC2 instances are running during normal operations, minimizing costs. The instances can be launched and initialized in less than 30 minutes during a DR event.
Achieves the Pilot Light/Warm Standby hybrid pattern that satisfies the low-cost and time-bound requirements.
3
Establish network routing and failover automation.
Using Route 53 failover routing with health checks allows traffic to be automatically redirected to the secondary region's Application Load Balancer once the compute tier is scaled up and the secondary database is promoted.
Enables automated failover routing without manual DNS updates.

Key Concept

Multi-region disaster recovery design using Pilot Light patterns to balance recovery objectives (RTO/RPO) with operational costs.
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Topics

High Availability and Disaster Recovery Design

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