snapbtr

snapbtr is a small utility that keeps snapshots of btrfs filesystems.

It is originally written by Helge Jensen (https://btrfs.wiki.kernel.org/index.php/SnapBtr). Re-published under the GPLv3 with his consent and blessing.

You can run it regularly (for example in a small script in cron.hourly), or once in a while, to maintain an "interesting" (see below) set of snapshots (backups). You may manually add or remove snapshots as you like, use 'snapbtr.DATE_FORMAT' (in GMT) as snapshot-name.

It will keep --target-backups snapshots on the file-system by selecting snapshots to remove.

Using --preserve-days, you can ensure that the most recent snapshots, which are taken within last N days are not deleted.

snapnbtr will keep backups with exponentially increasing distance as you go back in time. It does this by selecting snapshots to remove as follows.

The snapshots to remove is selected by "scoring" each space between snapshots, (newer,older). snapbtr will remove the older of the two snapshots in the space that have the lowest score.

The scoring mechanism integrates e^x from (now-newer) to (now-older) so, new pairs will have high value, even if they are tightly packed, while older pairs will have high value if they are far apart.

The mechanism is completely self-contained and you can delete any snapshot manually or any files in the snapshots.

Root permissions are not required for creating snapshot, if user has an ownership of the subvolume. This makes it possible to run "snapbtr -s" from a user application prior any modification done by this application (e.g. snapshot a maildir before receiving new emails). And periodically run "snapbtr -c" as root to cleanup.

Examples

Snapshot maildir before synchronization

snapbtr -s ~/email/store ~/email/backups

From all the backups which older then 5 days, keep only 100.

./snapbtr -c /mnt/backups  --target-backups 100 --preserve-days 5

Do the same, but create the snapshot at first

./snapbtr -cs ~/email/store ~/email/backups  --target-backups 100 --preserve-days 5

Install

sudo python2 setup.py install

Authors

• Helge Jensen hej@actua.dk
• Yuri Volchkov yuri.volchkov@gmail.com

Licensed under GPLv3 (or later) http://www.gnu.org/licenses/gpl-3.0.txt