Why does deleting a Synology Hyper Backup version free less space than expected?

Applies to: Hyper Backup multi-version repositories, including local, remote NAS and supported cloud destinations.

Work through these checks

1. Check the task's status and destination capacity in Hyper Backup. Allow an active backup or rotation operation to finish before judging the result.
2. Review the retention policy and the versions still required for recovery. Source files deleted today may remain deliberately recoverable in older backup versions.
3. Use Hyper Backup's version-management and rotation controls to remove only versions your retention policy allows. Never delete individual files inside an .hbk repository using File Station or a cloud file browser.
4. Compare the repository's actual destination usage before and after rotation completes. Compression, deduplication and destination-side snapshots or versioning can make this differ from the source's file sizes.

Confirm the result

Confirm that retained restore points can still be browsed and that the task reports a completed operation. Space recovery depends on which blocks remain referenced; no fixed percentage is guaranteed.

If you need help

Include these details in your ticket: Destination type, task status/log, retention settings and before/after capacity figures.

Updated 261107