BORG-COMPACT(1) borg backup tool BORG-COMPACT(1)

borg-compact - Collect garbage in repository

borg [common options] compact [options]

Free repository space by deleting unused chunks.

borg compact analyzes all existing archives to find out which repository objects are actually used (referenced). It then deletes all unused objects from the repository to free space.

Unused objects may result from:

  • borg delete or prune usage
  • interrupted backups (maybe retry the backup first before running compact)
  • backup of source files that had an I/O error in the middle of their contents and that were skipped due to this
  • corruption of the repository (e.g. the archives directory having lost entries, see notes below)

You usually don't want to run borg compact after every write operation, but either regularly (e.g. once a month, possibly together with borg check) or when disk space needs to be freed.

Important:

After compacting it is no longer possible to use borg undelete to recover previously soft-deleted archives.

borg compact might also delete data from archives that were "lost" due to archives directory corruption. Such archives could potentially be restored with borg check --find-lost-archives [--repair], which is slow. You therefore might not want to do that unless there are signs of lost archives (e.g. when seeing fatal errors when creating backups or when archives are missing in borg repo-list).

See borg-common(1) for common options of Borg commands.

# compact segments and free repo disk space
$ borg compact


borg-common(1)

The Borg Collective

2025-01-07