Which solution will meet these requirements MOST cost-effectively?
Use RDS automated snapshots. Create an AWS Lambda function to copy the snapshot to a second Region.
Use RDS automated snapshots every 6 hours. Use Amazon S3 Cross-Region Replication to copy the snapshot to a second Region.
Use AWS Backup to take an RDS snapshot every 6 hours and to copy the snapshot to a second Region.
Create an RDS cross-Region read replica in a second Region. Use AWS Backup to take an automated snapshot of the read replica every 6 hours.
Explanations:
RDS automated snapshots are region-specific, and Lambda functions would not be the most efficient or cost-effective method to replicate snapshots to a second Region.
S3 Cross-Region Replication is not designed for RDS snapshots, making this option incorrect for replicating RDS snapshots across Regions.
AWS Backup allows automated RDS snapshot creation and cross-region copying in a cost-effective manner, meeting the 6-hour RPO and disaster recovery requirements.
Creating a cross-Region read replica incurs additional costs and overhead. Automated snapshots of the read replica are not the most cost-effective solution for this scenario.
I chart that the answer is:
Use AWS Backup to take an RDS snapshot every 6 hours and to copy the snapshot to a second Region.