Inactive RDS Read Replica

However, it's common for replicas to remain in place even after their intended purpose has passed. In some cases, they were provisioned for scaling or analytics workloads that no longer exist; in others, they are tied to live environments but not actively receiving queries. Since each replica incurs full RDS costs, retaining one that is no longer used leads to unnecessary ongoing expenses.

Amazon RDS pricing is based on several components:

Compute

Billed hourly based on the instance type and size of each database instance, including read replicas

Storage

Charged per GB provisioned, regardless of usage

I/O Operations

Additional charges for reads and writes, depending on storage type

Data Transfer

Especially relevant for cross-region replication

Read replicas are billed as independent RDS instances, meaning they incur the same base costs as a standard instance-whether or not they are actively serving traffic.

• Identify all existing RDS read replicas and their associated primary instances
• Assess whether read traffic is being actively routed to each replica
• Review recent query activity to determine if the replica is used for reporting, analytics, or scaling
• Evaluate whether the replica is still needed for its original purpose (e.g., disaster recovery, cross-region availability, performance optimization)
• Confirm there are no active failover configurations or application connections relying on the replica
• Validate with relevant teams (e.g., DBA, application owners) that decommissioning the replica will not impact availability, performance, or redundancy

If a read replica is no longer receiving queries and has no clear operational or redundancy purpose, it should be deleted to avoid unnecessary compute and storage costs. Coordinate with database and application teams before removal to ensure that dependencies or failover plans are not disrupted.

• Amazon RDS Pricingaws.amazon.com
• Working with DB instance read replicasdocs.aws.amazon.com