Google Cloud DMS enables SQL Server disk shrinking for Cloud SQL instances

DMS Expands Capabilities for SQL Server

Google Cloud's Database Migration Service (DMS) now supports Cloud SQL for SQL Server as a source. This extends DMS functionality beyond traditional database migrations, allowing for continuous, low-downtime database replication between Cloud SQL instances. Replication can occur within the same project, across different projects, or across regions.

Addressing Disk Growth in Databases

Database storage typically increases over time due to features like automatic storage growth in Cloud SQL, which prevents outages during traffic spikes or large imports. While SQL Server marks freed space as reusable after data deletion or log truncation, the underlying database files retain their peak size unless manually shrunk. The `AUTO_SHRINK` setting is generally not recommended in production due to performance issues.

Shrinking Persistent Disks with DMS

Even after manually shrinking SQL Server database files using `DBCC SHRINKFILE`, the Cloud SQL persistent disk retains its peak allocated capacity. DMS provides a method to shrink the disk itself, which can reduce ongoing storage costs. This is particularly useful after major data archiving, purging, or recovering from one-time storage spikes where the active dataset is significantly smaller.

Operational Benefits

The ability to shrink persistent disks using DMS offers a non-traditional operational pattern for SQL Server customers within Google Cloud. By replicating to a smaller target instance and then redirecting applications, organizations can optimize storage costs for databases that have experienced significant data reduction, without incurring substantial downtime.