Which solution will meet these requirements?
Create an RDS read replica in the same AWS Region. Configure an AWS Lambda function to promote the replica as the primary DB instance during a DR scenario.
Create an RDS read replica in a different AWS Region. Configure an AWS Lambda function to promote the replica as the primary DB instance during a DR scenario.
Modify the DB instance to be a Multi-AZ deployment.
Setup an Amazon CloudWatch alarm that monitors the DB instance memory utilization with a threshold greater than 90%. Invoke an AWS Lambda function to restart the DB instance.
Explanations:
While an RDS read replica in the same region can be promoted, it does not provide automatic failover. A Lambda function is not ideal for disaster recovery because it requires manual intervention.
An RDS read replica in a different region provides geographic redundancy, but failover is not automatic. Manual promotion via Lambda is also not a fully automated failover solution.
Multi-AZ deployments provide automatic failover in the event of a failure. Data is replicated synchronously across AZs, ensuring no committed transactions are lost.
Monitoring memory utilization and restarting the DB instance via Lambda is not a solution for automatic failover and does not ensure no loss of committed transactions.
I value that the answer is:
Modify the DB instance to be a Multi-AZ deployment.