Re: restic backup with btrfs /

[Ulli Horlacher <framstag@rus.uni-stuttgart.de>]

On Thu 2025-07-03 (10:00), Robert Krig wrote:

> Why don't you just create a backup script, where you create a list of
> subvolumes dynamically and then back those up, rather than hardcode
> specific subvolumes?

Indeed, this is my plan :-)
I have used "harcoded subvolumes" only as a simple example to demonstrate
my idea.


> I would use btrfs tools to get a list of subvolumes and their paths,

With standard btrfs commands this is not easy, but I have already written
btrfs_list which does this job:

root@fex:~# btrfs_list /local/test
ACCESS-MODE SUBVOLUME <- SNAPSHOT-PARENT
rw /local/test
ro /local/test/.snapshot/2025-06-29_1414.test <- /local/test
ro /local/test/.snapshot/2025-06-29_1416.test <- /local/test
ro /local/test/.snapshot/2025-06-29_1418.test <- /local/test
rw /local/test/sv1
rw /local/test/sv1/sv1_1
rw /local/test/sv1/sv1_1/ss <- /local/test/sv1/sv1_1
rw /local/test/sv1/sv1_2
rw /local/test/sv2


> create snapshots and mount them in a similar directory tree and point
> restic at the snapshot and backup up from there.

In this case ".snapshot" is in the restic path, which I do not like.
Therefore I will use mount --bind ...

Meanwhile I have written btrfs_rsnapshot to create and delete snapshots of
nested subvolumes recursivly. Example:

root@fex:~# btrfs_rsnapshot /local
Create a snapshot of '/local' in '/local/.snapshot/_local'
Create a snapshot of '/local/home' in '/local/.snapshot/_local/home'
Create a snapshot of '/local/home/framstag/blubb' in '/local/.snapshot/_local/home/framstag/blubb'
Create a snapshot of '/local/home/smc/test' in '/local/.snapshot/_local/home/smc/test'
Create a snapshot of '/local/test' in '/local/.snapshot/_local/test'
Create a snapshot of '/local/test/sv1' in '/local/.snapshot/_local/test/sv1'
Create a snapshot of '/local/test/sv1/sv1_1' in '/local/.snapshot/_local/test/sv1/sv1_1'
Create a snapshot of '/local/test/sv1/sv1_1/ss' in '/local/.snapshot/_local/test/sv1/sv1_1/ss'
Create a snapshot of '/local/test/sv1/sv1_2' in '/local/.snapshot/_local/test/sv1/sv1_2'
Create a snapshot of '/local/test/sv2' in '/local/.snapshot/_local/test/sv2'
Create a snapshot of '/local/tmp/test' in '/local/.snapshot/_local/tmp/test'

root@fex:~# btrfs_rsnapshot -d /local
Delete subvolume (no-commit): '/local/.snapshot/_local/tmp/test'
Delete subvolume (no-commit): '/local/.snapshot/_local/test/sv2'
Delete subvolume (no-commit): '/local/.snapshot/_local/test/sv1/sv1_2'
Delete subvolume (no-commit): '/local/.snapshot/_local/test/sv1/sv1_1/ss'
Delete subvolume (no-commit): '/local/.snapshot/_local/test/sv1/sv1_1'
Delete subvolume (no-commit): '/local/.snapshot/_local/test/sv1'
Delete subvolume (no-commit): '/local/.snapshot/_local/test'
Delete subvolume (no-commit): '/local/.snapshot/_local/home/smc/test'
Delete subvolume (no-commit): '/local/.snapshot/_local/home/framstag/blubb'
Delete subvolume (no-commit): '/local/.snapshot/_local/home'
Delete subvolume (no-commit): '/local/.snapshot/_local'


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum TIK
Universitaet Stuttgart         E-Mail: horlacher@tik.uni-stuttgart.de
Allmandring 30a                Tel:    ++49-711-68565868
70569 Stuttgart (Germany)      WWW:    https://www.tik.uni-stuttgart.de/
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