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

An online multiplayer gaming company hosts its matchmaking and leaderboard platform in the us-east-1 Region. The backend application runs on Amazon EC2 instances behind an Application Load Balancer (ALB), and data is stored in an Amazon RDS for PostgreSQL database. The company wants to establish a disaster recovery (DR) plan in the us-west-2 Region. The solution must meet a 3030-minute Recovery Time Objective (RTO) and a 55-minute Recovery Point Objective (RPO) while minimizing ongoing infrastructure costs. Which strategy should a solutions architect recommend to meet these requirements?

  1. Implement a Pilot Light recovery strategy in the us-west-2 Region. Set up Amazon RDS cross-region replication to continuously replicate database writes. Keep application servers stopped or deploy them dynamically via AWS CloudFormation and pre-configured Amazon Machine Images (AMIs) during a failover event.Answer
  2. B
    Deploy a Warm Standby architecture in the us-west-2 Region. Maintain active cross-region database replication and run a scaled-down fleet of application EC2 instances continuously. Scale up the application fleet and adjust DNS routing during a failover event.
  3. C
    Set up an Amazon RDS cross-region read replica in the us-west-2 Region. Configure Amazon Route 53 with latency-based routing and no health checks to automatically direct matchmaking write traffic directly to the read replica during an outage.
  4. D
    Configure daily database backups using AWS Backup, storing them in Amazon S3 Glacier Flexible Retrieval in the us-west-2 Region. In the event of a disaster, restore the database from Glacier and launch the application EC2 instances using AWS CloudFormation.

Answer

Implement a Pilot Light recovery strategy in the us-west-2 Region by setting up Amazon RDS cross-region replication to continuously replicate database writes, and keeping application servers stopped or deploying them dynamically via AWS CloudFormation and pre-configured AMIs during a failover event.
The correct strategy is the Pilot Light setup. This option meets the 55-minute RPO by continuously replicating the primary database to the disaster recovery region using Amazon RDS cross-region replication. It also meets the 3030-minute RTO because application servers can be started or provisioned from pre-configured AMIs and CloudFormation templates within that time frame. Because the application compute resources are kept shut down or unprovisioned until failover, ongoing operational costs are minimized.

Step-by-Step Solution

1
Analyze the RTO and RPO requirements.
The target RTO is 3030 minutes (maximum acceptable downtime) and the target RPO is 55 minutes (maximum acceptable data loss).
This determines which DR strategy and replication technologies are viable.
2
Evaluate replication methods for the database to meet the 55-minute RPO constraint.
AWS Backup with daily backups fails the RPO. Amazon RDS cross-region read replicas continuously replicate data asynchronously, keeping data lag typically under a few minutes, which satisfies the 55-minute RPO.
Continuous database replication is required to avoid losing more than 55 minutes of data.
3
Select the most cost-effective compute deployment that satisfies the 3030-minute RTO.
A Pilot Light strategy allows compute resources (EC2 instances) to remain turned off or unprovisioned, and then started or created from AMIs within 3030 minutes. This is more cost-effective than Warm Standby, which keeps scaled-down instances running continuously.
Since the RTO is 3030 minutes, there is sufficient time to spin up instances dynamically, avoiding the cost of idle running instances.

Key Concept

Disaster Recovery strategies (Pilot Light vs. Warm Standby) and cross-region replication capabilities.
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Topics

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

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