Which DR strategy will meet these requirements with the LEAST change to the application stack?
Launch a replica environment of everything except Amazon RDS in a different Availability Zone. Create an RDS read replica in the new Availability Zone, and configure the new stack to point to the local RDS DB instance. Add the new stack to the Route 53 record set by using a health check to configure a failover routing policy.
Launch a replica environment of everything except Amazon RDS in a different AWS Region. Create an RDS read replica in the new Region, and configure the new stack to point to the local RDS DB instance. Add the new stack to the Route 53 record set by using a health check to configure a latency routing policy.
Launch a replica environment of everything except Amazon RDS in a different AWS Region. In the event of an outage, copy and restore the latest RDS snapshot from the primary Region to the DR Region. Adjust the Route 53 record set to point to the ALB in the DR Region.
Launch a replica environment of everything except Amazon RDS in a different AWS Region. Create an RDS read replica in the new Region, and configure the new environment to point to the local RDS DB instance. Add the new stack to the Route 53 record set by using a health check to configure a failover routing policy. In the event of an outage, promote the read replica to primary.
Explanations:
While this option allows for a local disaster recovery setup in a different Availability Zone, it does not meet the geographical isolation requirement for a DR site. The RTO and RPO requirements could be challenging to meet since it relies on a single region, limiting recovery capabilities in case of a major regional failure.
This option launches a replica environment in a different AWS Region, which is necessary for geographical isolation. However, configuring the new stack to point to the local RDS DB instance does not provide the needed data redundancy for the RPO of 15 minutes, as it relies on the primary DB instance without a mechanism for quick failover.
This option provides geographical isolation by launching a replica environment in a different AWS Region. However, it requires manual intervention to copy and restore the RDS snapshot in the event of an outage, which would likely result in a recovery time exceeding the required RTO of 4 hours. Therefore, it does not meet the operational recovery objectives.
This option meets the requirement for geographical isolation by deploying a replica environment in a different AWS Region. It also includes creating an RDS read replica, allowing for near-real-time data replication, thus meeting the RPO of 15 minutes. In case of an outage, promoting the read replica to primary ensures quick recovery, supporting the RTO of 4 hours effectively.
I would say the answer is:
Launch a replica environment of everything except Amazon RDS in a different AWS Region. Create an RDS read replica in the new Region, and configure the new environment to point to the local RDS DB instance. Add the new stack to the Route 53 record set by using a health check to configure a failover routing policy. In the event of an outage, promote the read replica to primary.