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Difficulty: EasyDisaster Recovery Strategies

A company runs a production web application on AWS. The application tier consists of stateless Amazon EC2 instances, and the data tier uses an Amazon RDS for PostgreSQL database instance. A SysOps administrator must implement a cross-region disaster recovery (DR) strategy with a Recovery Time Objective (RTO) of 4 hours and a Recovery Point Objective (RPO) of 24 hours. The strategy must minimize ongoing costs. Which DR strategy should the administrator implement to meet these requirements?

  1. A
    Configure a pilot light strategy by deploying a standby EC2 instance in the recovery region and setting up a cross-region RDS Read Replica to serve as the automatic, synchronous failover target.
  2. B
    Configure a warm standby strategy by deploying a fully functional, active-active multi-site architecture across both regions, and use Route 53 failover routing without associating health checks with the primary DNS record.
  3. Configure AWS Backup to take daily snapshots of the database and EC2 instances, copy them to the recovery region, and deploy the infrastructure using AWS CloudFormation templates only during a failover event.Answer
  4. D
    Configure an S3 bucket in the recovery region to store database backups, and enable S3 Cross-Region Replication (CRR) from the primary bucket without enabling versioning on the source bucket.

Answer

Configure AWS Backup to take daily snapshots of the database and EC2 instances, copy them to the recovery region, and deploy the infrastructure using AWS CloudFormation templates only during a failover event.
The Backup and Restore strategy satisfies both RTO and RPO requirements at the lowest cost. Taking daily backups satisfies the 24-hour RPO, and copying them to a secondary region allows restoration within 4 hours (RTO) using CloudFormation to deploy resources on-demand. This avoids the running costs associated with Pilot Light, Warm Standby, or Multi-site strategies.

Step-by-Step Solution

1
Analyze RTO and RPO requirements.
The target RTO is 4 hours (acceptable recovery time), and RPO is 24 hours (acceptable data loss up to 24 hours).
Determines which DR strategy satisfies the requirements while minimizing costs.
2
Evaluate the cost-effectiveness of DR strategies.
Backup and Restore has the lowest cost because it does not keep active compute resources running in the secondary region.
Selecting the strategy that matches the 'minimize ongoing costs' constraint.
3
Confirm technical feasibility of Backup and Restore.
Daily backups copied to the secondary region satisfy the 24-hour RPO. Restoring the database from snapshots and deploying stateless instances using CloudFormation can easily be completed within 4 hours, satisfying the RTO.
Ensures the selected option meets all specified targets.

Key Concept

Disaster Recovery Strategies
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Topics

Disaster Recovery Strategies

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