btrfs-backup is a program for backing up btrfs subvolumes in an
incremental fashion.
btrfs-backup is written in Rust and requires the Cargo package
manager to be built. It can be installed using cargo install
btrfs-backup. The program requires btrfs-progs to be
installed and its btrfs binary to be discoverable via the PATH
environment variable.
Let's say you have two subvolumes that you would like to back up to
some external HDD mounted at /mnt/backup:
sh
$ mount /mnt/backup/
$ mkdir /.tmpjWzWMn/
$ mkdir /.tmpjWzWMn/subdir
$ btrfs subvolume create /.tmpjWzWMn/subvol1
$ btrfs subvolume create /.tmpjWzWMn/subdir/subvol2
Then backup can be as simple as:
sh
$ btrfs-backup backup /.tmpjWzWMn/subvol1 /.tmpjWzWMn/subdir/subvol2 --destination /mnt/backup/
This command results in the following backup snapshots: ```sh $ ls -l /mnt/backup/
drwxr-xr-x 1 root root 0 Feb 20 11:13
.tmpjWzWMn-subdir-subvol22023-02-2011:14:35 drwxr-xr-x 1 root root 0 Feb 20 11:13 .tmpjWzWMn-subvol12023-02-2011:14:35 ```
The way backups work on a btrfs file system, a read-only snapshot of
the subvolume to back up is created on the source file system and then
send over to the destination file system. Shown above are the snapshots
on the destination file system. Because we did not provide the
--source argument to the command, snapshots on the source file system
are co-located with the actual subvolume in question (that is, they
reside in the same parent directory):
```sh
$ ls -al /.tmpjWzWMn/
drwxr-xr-x 1 root root 0 Feb 20 11:13 nuc.tmpjWzWMn-subvol12023-02-20_11:14:35 drwxr-xr-x 1 root root 112 Feb 20 11:14 subdir drwxr-xr-x 1 root root 0 Feb 20 11:13 subvol1 ```
If you want to have snapshots centrally managed, provide the --source
flag with a path to a directory on the btrfs file system on which the
subvolumes to back up are located.
Please refer to the help text (--help) for additional details.
The program supports backup and restoration of subvolumes on a single system, as well as cleaning up of stale snapshots. As such, it is fully usable for backup needs.
Compared to the original Python version of the
program, the snapshot naming scheme has changed and a few bugs have been
fixed. Support for remote backups (over ssh) as well as backups to
files is not yet present.