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Difficulty: MediumDisaster Recovery Strategies

A company operates a legacy accounting platform on AWS. The application tier runs on a fleet of Amazon EC2 instances, and the database tier uses an Amazon RDS for MySQL DB instance. A SysOps Administrator is designing a cost-effective Pilot Light disaster recovery (DR) strategy in a secondary Region. The strategy must achieve a Recovery Point Objective (RPO) of 1 hour and a Recovery Time Objective (RTO) of 4 hours.

Which two actions should the SysOps Administrator take to meet these requirements?

  1. Create a cross-region read replica of the RDS for MySQL DB instance in the secondary Region.Answer
  2. Configure an Auto Scaling group in the secondary Region with the minimum and desired capacity set to 0, referencing an Amazon Machine Image (AMI) copied from the primary Region.Answer
  3. C
    Configure the RDS for MySQL DB instance with Multi-AZ replication to automatically fail over to the secondary Region.
  4. D
    Configure an Amazon Route 53 active-active failover routing policy to distribute traffic equally between the application servers in both Regions.
  5. E
    Enable Amazon S3 Cross-Region Replication (CRR) for application asset buckets without enabling versioning on the source or destination buckets.

Answer

Create a cross-region read replica of the RDS for MySQL DB instance in the secondary Region, and configure an Auto Scaling group in the secondary Region with the minimum and desired capacity set to 0, referencing an Amazon Machine Image (AMI) copied from the primary Region.
The correct solution uses a Pilot Light disaster recovery model to minimize costs. By deploying an RDS cross-region read replica, the database is kept up to date asynchronously, satisfying the 1-hour RPO. Scaling the application tier Auto Scaling group in the recovery region to 0 instances ensures there are no ongoing compute costs, while allowing the infrastructure to spin up rapidly within the 4-hour RTO during failover.

Step-by-Step Solution

1
Select the cross-region replication method that meets the RPO constraint.
Identify that a cross-region read replica for RDS for MySQL asynchronously replicates database updates to the secondary Region with a lag typically under a few minutes, satisfying the 1-hour RPO requirement.
This establishes a passive, cost-effective database standby that can be promoted during disaster recovery.
2
Determine the application tier DR provisioning strategy that meets the RTO and cost constraints.
Configure an Auto Scaling group in the secondary Region with minimum and desired capacities set to 0, using a pre-copied AMI.
This configuration incurs no EC2 compute charges during normal operation, fulfilling the Pilot Light model requirements, and allows fast scaling within the 4-hour RTO when failover is triggered.

Key Concept

Pilot Light Disaster Recovery Strategy
Estimated Time:2m 0s
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Topics

Disaster Recovery Strategies

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