Recovering from “no free space” errors

In some cases when a repository has grown large enough to fill up all disk space or the allocated quota, then prune might fail to free space. prune works in such a way that a repository remains usable no matter at which point the command is interrupted. However, this also means that prune requires some scratch space to work.

In most cases it is sufficient to instruct prune to remove all packs marked for removal and use as little scratch space as possible. Note that packs marked for removal are automatically removed by a prune run once they are old enough. If you can guarantee that the repository is not used by parallel processes, you can also use rustic prune --instant-delete.

To use as little scratch space as possibe, run rustic prune --max-repack-size 0 --instant-delete (and make sure no parallel process acesses the repository!). This removes all unneeded packs without repacking partly used packs. You may need to remove some snapshots using forget before. This then allows the prune command to actually remove data from the repository. If the command succeeds, but there is still little free space, then remove a few more snapshots and run prune again.

In cases where the above commands do not work, prune fails because it first writes modified index files before removing old ones. To first remove the no-loger used index files, use rustic prune --max-repack-size 0 --instant-delete --early-delete-index. Note that if this prune run is aborted for some reasons, you first must rebuild your index.