Inactive DMS Replication Instance

Tom Cross

Service Category

Database

Cloud Provider

AWS

Service Name

AWS DMS

Inefficiency Type

Orphaned Resource

Explanation

Replication instances are commonly left running after migration tasks are completed, especially when DMS is used for one-time or project-based migrations. Without active replication tasks, these instances no longer serve any purpose but continue to incur hourly compute costs. In large organizations or decentralized migration projects, these idle instances may go unnoticed, contributing to persistent background spend.

Relevant Billing Model

DMS Replication Instances are charged per hour of uptime, based on instance size
Charges accrue even if no replication tasks are actively running
Additional storage charges may apply for logs and cached data, but the bulk of cost comes from the instance itself

Detection

List all DMS replication instances in the account or region
Check whether each instance has active replication tasks associated with it
Flag instances with zero tasks or tasks in a stopped or completed state
Review instance creation and last activity timestamps to identify long-idle resources

Remediation

Stop and delete DMS replication instances that are no longer associated with active or planned tasks
Tag replication instances by project or migration wave to enable future clean-up
Incorporate DMS instance lifecycle checks into post-migration workflows
Use infrastructure-as-code where possible to ensure temporary resources are cleaned up automatically

Relevant Documentation