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Difficulty: EasyHigh Availability and Disaster Recovery Design

A digital publishing company wants to establish a cross-region disaster recovery (DR) plan for its archive metadata repository. The repository has a target Recovery Time Objective (RTO) of 12 hours and a Recovery Point Objective (RPO) of 24 hours. The architecture must minimize ongoing infrastructure costs in the secondary Region during normal operations. Which two actions should a solutions architect recommend to meet these requirements? (Select TWO.)

  1. Use AWS Backup to schedule daily backups of the database and copy them to the secondary Region.Answer
  2. Deploy the application's EC2 instances and load balancers using AWS CloudFormation only after a disaster is declared.Answer
  3. C
    Provision an Amazon RDS Read Replica in the secondary Region to continuously replicate database updates.
  4. D
    Configure an Amazon Route 53 Geoproximity routing policy to load-balance user requests across both Regions.
  5. E
    Keep a scaled-down version of the application stack running continuously in the secondary Region.

Answer

Use AWS Backup to schedule daily backups of the database and copy them to the secondary Region, and deploy the application's EC2 instances and load balancers using AWS CloudFormation only after a disaster is declared.
For a 24-hour RPO, daily database backups are sufficient to ensure that no more than 24 hours of data is lost. For a 12-hour RTO, there is enough time to construct the application infrastructure from scratch. By using AWS Backup to copy daily database backups and using AWS CloudFormation to deploy the compute and network resources only when a disaster occurs, the company can meet its objectives while keeping ongoing idle resource costs in the secondary Region at zero.

Step-by-Step Solution

1
Analyze RTO, RPO, and cost constraints.
The target RTO is 12 hours, target RPO is 24 hours, and ongoing costs must be minimized by avoiding idle resources.
Understanding these boundaries allows the selection of the most cost-effective disaster recovery strategy.
2
Determine the database recovery method that meets the 24-hour RPO.
A backup taken once daily and copied to the secondary Region satisfies the 24-hour RPO.
AWS Backup can schedule and copy backups across Regions, avoiding active replication costs.
3
Determine the infrastructure recovery method that meets the 12-hour RTO.
Using AWS CloudFormation to spin up the infrastructure on-demand meets the 12-hour RTO without running resources in advance.
CloudFormation can provision load balancers and EC2 instances within minutes, which is well within the 12-hour limit.

Key Concept

Selecting the most cost-effective disaster recovery strategy (Backup and Restore) when RTO and RPO limits are lenient enough to avoid active resources.
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Topics

High Availability and Disaster Recovery Design

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