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Difficulty: MediumHigh Availability and Disaster Recovery Design

A financial services company is designing a disaster recovery (DR) architecture for a critical web application. The primary environment runs in the `us-east-1` Region, and the DR environment will be deployed in the `us-west-2` Region. The business requirements specify a Recovery Time Objective (RTO) of 15 minutes and a Recovery Point Objective (RPO) of 2 minutes. The architecture must be highly available and resilient to single-zone failures in both regions while keeping ongoing standby costs as low as possible. Which solution meets these requirements?

  1. A
    Deploy the application in `us-east-1` and `us-west-2` across three Availability Zones. Set up Amazon Aurora Global Database to replicate the database. To minimize standby costs in the disaster recovery region, deploy a single NAT Gateway in one Availability Zone in `us-west-2` and configure private subnets across all three zones to route outbound traffic through it. Configure Amazon Route 53 with Failover routing.
  2. Deploy the application in `us-east-1` using Amazon Aurora PostgreSQL. Create an Amazon Aurora Global Database with a secondary cluster in `us-west-2` containing a single db.r6g.large reader instance. Set up Application Load Balancers in both regions. Configure Amazon Route 53 with an Active-Passive Failover routing policy and health checks pointing to the Application Load Balancer in each region. Promote the secondary cluster if the primary region fails.Answer
  3. C
    Deploy the application in `us-east-1` with Amazon Aurora PostgreSQL. Configure AWS Backup to take hourly database snapshots and copy them to `us-west-2`. Pre-deploy application servers in `us-west-2` using AWS CloudFormation in a stopped state. During an outage, restore the database from the copied snapshot and start the application servers.
  4. D
    Deploy the application in `us-east-1` using Amazon RDS for PostgreSQL in a Multi-AZ configuration. Set up an Amazon RDS read replica in `us-west-2`. To minimize database cost and performance impact during normal operations, route all reporting read traffic directly to the passive Multi-AZ standby instance located in the secondary Availability Zone of the primary region.

Answer

Deploy the application in the primary region using Amazon Aurora PostgreSQL, configure an Aurora Global Database with a secondary cluster containing a single reader instance in the disaster recovery region, set up Application Load Balancers in both regions, and use Route 53 Failover routing with health checks to manage the failover.
The correct solution utilizes Amazon Aurora Global Database, which replicates data asynchronously to a secondary region with latency typically under 1 second, meeting the 2-minute RPO. Promoting the secondary cluster takes only a few minutes, meeting the 15-minute RTO. Having a single replica instance in the secondary region minimizes standby costs, and using Route 53 Active-Passive Failover routing with health checks automates traffic redirection.

Step-by-Step Solution

1
Evaluate the database replication strategy to satisfy the 2-minute RPO.
Amazon Aurora Global Database provides cross-region replication lag of less than 1 second, meeting the 2-minute RPO requirement, unlike hourly snapshots which have up to a 60-minute RPO.
Selecting the correct replication method is necessary to guarantee data recovery boundaries.
2
Select a disaster recovery pattern that satisfies the 15-minute RTO.
Aurora Global Database allows cluster promotion in under 5 minutes. Combined with Route 53 Active-Passive Failover routing, the entire recovery process takes less than 15 minutes.
An active-passive warm standby/pilot light setup ensures that resources are pre-provisioned or quickly promotable to meet recovery timelines.
3
Verify high availability and cost constraints in the secondary region.
To maintain high availability, NAT Gateways must be deployed in each Availability Zone in the DR region. Standby costs are kept low by using a single reader instance that can be scaled up during promotion.
Ensuring the secondary region contains no single points of failure while minimizing the size of standby compute satisfies both high availability and cost requirements.

Key Concept

Cross-region disaster recovery using Amazon Aurora Global Database and Route 53 Active-Passive Failover to meet strict RTO/RPO and HA requirements.
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Topics

High Availability and Disaster Recovery Design

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