This solution represents a warm standby approach, which is optimal for minimizing recovery time (RTO) as required. By pre-provisioning the Amazon ECS cluster and service in the disaster recovery (DR) Region, the application compute layer is ready to accept traffic. Using a cross-Region read replica for the Amazon RDS database ensures that data is continuously and asynchronously replicated. During a failover, the process is swift: the Lambda function promotes the read replica to a standalone, writable primary instance and updates the Amazon Route 53 DNS record. This promotion process is significantly faster than creating a new database instance from a snapshot, directly meeting the requirement to minimize recovery time.

A. Restoring an RDS instance from a snapshot is a time-consuming process that results in a higher Recovery Time Objective (RTO) compared to promoting a read replica.

B. This option is even slower than A because it creates the ECS infrastructure during the failover event, in addition to the slow RDS snapshot restore process.

D. Converting a relational RDS snapshot to a DynamoDB global table during a disaster is technically complex, slow, and would likely require significant application code changes.

1. AWS Documentation

Amazon RDS User Guide: "You can use read replicas for disaster recovery... To use a read replica for disaster recovery

you promote the read replica. When you promote a read replica

it becomes a standalone DB instance." This guide details the process for "Promoting a read replica to be a standalone DB instance."

2. AWS Whitepaper

Disaster Recovery (DR) Architecture on AWS

Part III: Pilot Light and Warm Standby: This paper describes the Warm Standby approach. "In the case of disaster

the warm standby site can be scaled up to handle the full production load... For databases

you can use native features such as SQL Server Always On

Oracle Data Guard

or MySQL/PostgreSQL replication to a warm standby." (Page 5). This aligns with using an RDS read replica.

3. AWS Well-Architected Framework

Reliability Pillar: "Use a warm standby in a different AWS Region. This approach decreases the recovery time because your data is live in the other Region and the core infrastructure is running." This directly supports the chosen architecture of having running infrastructure (ECS) and a replicated database (RDS Read Replica). (Section: "Plan for disaster recovery (DR)").