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

A company runs a car rental reservation portal in a single AWS Region. The application uses an Amazon RDS for MySQL DB instance. The company needs to establish a disaster recovery (DR) strategy in a secondary Region. The strategy must meet a Recovery Point Objective (RPO) of 24 hours and a Recovery Time Objective (RTO) of 4 hours. Which solution meets these requirements at the lowest cost?

  1. A
    Deploy a warm standby database replica in the secondary Region with a continuously running, scaled-down RDS DB instance to guarantee immediate database failover.
  2. Configure automated daily snapshots of the RDS DB instance and copy them to the secondary Region. In the event of a disaster, use AWS CloudFormation to deploy the application resources and restore the database from the copied snapshot.Answer
  3. C
    Create an RDS Read Replica in the secondary Region, and configure Amazon Route 53 latency routing to automatically promote the replica and redirect database write traffic during a failover.
  4. D
    Configure daily database backups, store them in Amazon S3 Glacier Flexible Retrieval in the secondary Region, and use standard retrieval to restore the database in the event of a disaster.

Answer

Configure automated daily snapshots of the RDS DB instance and copy them to the secondary Region. In the event of a disaster, use AWS CloudFormation to deploy the application resources and restore the database from the copied snapshot.
The Backup and Restore strategy using daily cross-region RDS snapshots and AWS CloudFormation templates is the most cost-effective option because it incurs zero active database or compute charges in the secondary Region. The daily snapshots satisfy the 24-hour Recovery Point Objective (RPO), and restoring the database and infrastructure can be completed within the 4-hour Recovery Time Objective (RTO).

Step-by-Step Solution

1
Analyze RPO and RTO requirements to determine the appropriate DR strategy.
An RPO of 24 hours indicates daily data loss is acceptable, pointing to daily backups/snapshots. An RTO of 4 hours allows enough time to provision infrastructure and restore the database from a backup.
Matching business continuity requirements with the correct DR strategy prevents over-engineering and minimizes costs.
2
Evaluate the cost of different DR options.
Backup and Restore (storing snapshots) is the most cost-effective strategy since it incurs only storage costs until a disaster occurs. Warm Standby and Read Replicas incur active, continuous compute and database instance costs.
The question asks for the lowest cost solution that meets the requirements.
3
Verify technical feasibility and correctness.
Daily snapshots meet the 24-hour RPO. Restoring RDS from a snapshot and launching resources via AWS CloudFormation can be easily completed within 4 hours. S3 Glacier Flexible Retrieval is ruled out because its 3-5 hour retrieval delay alone risks violating the 4-hour RTO.
Ensures the selected low-cost solution is technically capable of achieving the RTO and RPO targets.

Key Concept

Disaster Recovery (DR) strategies on AWS vary in cost and recovery times. Backup and Restore is the most cost-effective DR strategy for workloads that can tolerate an RTO and RPO of several hours, as it does not require running active compute or database instances in the recovery region.
Estimated Time:1m 0s
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Topics

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

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