Which solution will meet these requirements?
Create a cross-Region read replica of the DB instance. Promote the read replica at the time of failover.
Set up SQL replication from the DB instance to an Amazon EC2 instance in the disaster recovery Region. Promote the EC2 instance as the primary server.
Use AWS Database Migration Service (AWS KMS) for ongoing replication of the DB instance in the disaster recovery Region.
Take manual snapshots of the DB instance in the primary Region. Copy the snapshots to the disaster recovery Region.
Explanations:
Creating a cross-Region read replica provides near real-time replication of the database. In the event of a failover, the read replica can be promoted to become the primary database, ensuring minimal downtime and achieving the lowest possible RPO and RTO.
Setting up SQL replication from RDS to an EC2 instance is not an optimal solution for cross-Region disaster recovery. The EC2 instance would require manual intervention to promote it, and this method involves additional complexity and a higher RPO compared to using a read replica.
AWS Database Migration Service (DMS) is primarily used for migrating and replicating data from one database to another. While it can replicate data, it doesn’t support the low RPO and RTO required for a disaster recovery solution. DMS also doesn’t provide automatic promotion or failover functionality like RDS read replicas.
Taking manual snapshots and copying them to the disaster recovery Region introduces higher RPO and RTO because snapshots are not continuously updated. The snapshots are also not immediately usable as a live database without restoration, which leads to increased downtime during failover.
I would say the answer is:
Create a cross-Region read replica of the DB instance. Promote the read replica at the time of failover.