Start with the failure
Different features solve different problems. A failed compute instance, an accidentally deleted table, and a reporting workload that overwhelms the primary are not the same incident.
List the failure you need to survive before selecting a deployment option.
Availability keeps service running
A deployment with a managed failover capability can improve availability when an infrastructure component fails. The supported topology, reader behavior, and failover details vary by RDS engine and deployment type.
Applications still need sensible connection handling and retries. Existing connections may not survive a failover.
Recovery gets earlier data back
Replication can faithfully copy an unwanted change. If an application deletes the wrong records, a standby may receive that deletion too.
Backups and point-in-time recovery address a different requirement: reconstructing a database at an earlier state. Recovery procedures must include validation and application reconnection, not just creating a restored instance.
Read scaling has another purpose
Read replicas or readable instances can serve some read workloads, subject to the chosen engine's consistency and topology behavior.
Do not assume every standby is readable. In particular, distinguish RDS Multi-AZ DB instance deployments from Multi-AZ DB cluster deployments and Aurora architectures.
Make a recovery worksheet
Record the acceptable data-loss window, acceptable downtime, backup retention, encryption dependencies, restore permissions, and the person responsible for declaring a recovery complete.
Test the full restore procedure in a controlled environment. Check both data correctness and the time needed to make the application usable again.
Review costs and lifecycle
Additional instances, storage, backups, and cross-region transfers can create charges. Check the current service documentation and estimate costs for the exact configuration and region.
This guide does not create infrastructure. A hands-on deployment should include explicit teardown instructions and a decision about which backups to retain.