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Difficulty: EasyHigh Availability and Disaster Recovery Design

An organization is designing a disaster recovery (DR) architecture for a non-critical internal HR portal. The application currently runs on Amazon EC2 instances behind an Application Load Balancer, with data stored in an Amazon RDS for MySQL database. The business requires a Recovery Point Objective (RPO) of 24 hours and a Recovery Time Objective (RTO) of 4 hours. The architecture must minimize ongoing running costs in the secondary DR region. Which TWO options should the Solutions Architect implement to meet these requirements?

  1. Create daily snapshots of the Amazon RDS for MySQL database and copy them to the secondary AWS Region.Answer
  2. Create an Amazon Machine Image (AMI) of the EC2 instances, copy the AMI to the secondary AWS Region, and use AWS CloudFormation to deploy the compute infrastructure only when a disaster is declared.Answer
  3. C
    Deploy a standby database using Amazon RDS Multi-AZ across regions to act as the primary database in the secondary region.
  4. D
    Configure an Active-Active multi-region deployment using Amazon Aurora Global Database to replicate all data instantly.
  5. E
    Deploy a single NAT Gateway in one Availability Zone in the secondary region and route all subnets to it to minimize NAT costs during DR operations.

Answer

To meet the requirements, the Solutions Architect should copy daily database snapshots to the secondary region and use AWS CloudFormation with copied AMIs to deploy the compute resources only when a disaster occurs.
For an RTO of 4 hours and RPO of 24 hours, a Backup and Restore DR strategy is the most cost-effective solution. Copying daily database snapshots to the secondary region meets the 24-hour RPO, and using AWS CloudFormation along with copied AMIs to launch compute resources on-demand during a failover ensures the 4-hour RTO is met while keeping standby costs minimal.

Step-by-Step Solution

1
Analyze RTO and RPO requirements.
The target RTO is 4 hours and RPO is 24 hours, which allows for a Backup and Restore strategy. Active-Active or warm standby strategies are not necessary and would violate the low-cost constraint.
Determining the correct disaster recovery pattern prevents over-provisioning and minimizes cost.
2
Determine the database DR mechanism.
Daily snapshots meet the 24-hour RPO. Copying these snapshots to the secondary region ensures data is available for restoration within the 4-hour RTO.
Database snapshots stored in a different region provide a secure and low-cost backup solution.
3
Determine the compute DR mechanism.
Create AMIs in the primary region, copy them to the secondary region, and use CloudFormation templates to provision the load balancer and instances only when needed.
This avoids paying for idle compute capacity in the secondary region, aligning with the cost-optimization constraint.

Key Concept

Disaster Recovery strategies (Backup & Restore) vs cost and RTO/RPO objectives
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Topics

High Availability and Disaster Recovery Design

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