borgmatic/docs/reference/configuration/data-sources/zfs.md

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title: ZFS eleventyNavigation: key: • ZFS

parent: 🗄️ Data sources

New in version 1.9.3 Beta feature borgmatic supports taking snapshots with the ZFS filesystem and sending those snapshots to Borg for backup.

The minimum configuration to enable ZFS support is:

zfs:

Dataset discovery

You have a couple of options for borgmatic to find and backup your ZFS datasets:

• For any dataset you'd like backed up, add its mount point to borgmatic's source_directories option.
• New in version 1.9.6 Or include the mount point as a root pattern with borgmatic's patterns or patterns_from options.
• Or set the borgmatic-specific user property org.torsion.borgmatic:backup=auto onto your dataset, e.g. by running zfs set org.torsion.borgmatic:backup=auto datasetname. Then borgmatic can find and backup these datasets.

If you have multiple borgmatic configuration files with ZFS enabled, and you'd like particular datasets to be backed up only for particular configuration files, use the source_directories option instead of the user property.

New in version 1.9.11 borgmatic won't snapshot datasets with the canmount=off property, which is often set on datasets that only serve as a container for other datasets. Use zfs get canmount datasetname to see the canmount value for a dataset.

During a backup, borgmatic automatically snapshots these discovered datasets, temporarily mounts the snapshots within its runtime directory, and includes the snapshotted files in the paths sent to Borg. borgmatic is also responsible for cleaning up (destroying) these snapshots after a backup completes.

Additionally, borgmatic rewrites the snapshot file paths so that they appear at their original dataset locations in a Borg archive. For instance, if your dataset is mounted at /var/dataset, then the snapshotted files will appear in an archive at /var/dataset as well—even if borgmatic has to mount the snapshot somewhere in /run/user/1000/borgmatic/zfs_snapshots/ to perform the backup.

If a dataset has a separate filesystem mounted somewhere within it, that filesystem won't get included in the snapshot. For instance, if / is a ZFS dataset but /boot is a separate filesystem, borgmatic won't include /boot as part of the dataset snapshot. You can however add /boot to source_directories if you'd like it included in your backup.

New in version 1.9.4 borgmatic is smart enough to look at the parent (and grandparent, etc.) directories of each of your source_directories to discover any datasets. For instance, let's say you add /var/log and /var/lib to your source directories, but /var is a dataset. borgmatic will discover that and snapshot /var accordingly. This also works even with nested datasets; borgmatic selects the dataset that's the "closest" parent to your source directories.

New in version 1.9.6 When using patterns, the initial portion of a pattern's path that you intend borgmatic to match against a dataset can't have globs or other non-literal characters in it—or it won't actually match. For instance, a mount point of /var would match a pattern of + fm:/var/*/data, but borgmatic isn't currently smart enough to match /var to a pattern like + fm:/v*/lib/data.

With Borg version 1.2 and earlierSnapshotted files are instead stored at a path dependent on the runtime directory in use at the time the archive was created, as Borg 1.2 and earlier do not support path rewriting.

Performance

With Borg version 1.x Because of the way that ZFS snapshot paths can change from one borgmatic invocation to the next, the Borg file cache may not get cache hits on snapshotted files. This makes backing up ZFS snapshots a little slower than non-snapshotted files that have consistent paths. You can mitigate this by setting a fixed runtime directory) (that's not located in /tmp). This allows borgmatic to use a consistent snapshot path from one run to the next, thereby resulting in Borg files cache hits.

With Borg version 2.x Snapshotted files should get cache hits regardless of whether their paths change, because Borg 2.x is smarter about how it looks up file paths in its cache—it constructs the cache key with the path as it's seen in the archive (which is consistent across runs) rather than the full absolute source path (which can change).

Full configuration

{% include borgmatic/zfs.yaml %}