Backing up nested Btrfs sub volumes

absolution · July 7, 2021, 1:52pm

Hi everyone,

I’m running UrBackup in a docker container and running a UrBackup client on directly on the ubuntu host.
The file system for the ubuntu host is BTRFS.
I have a series of nested sub volumes e.g.

/ #one subvolume
/home #another sub volume
/usr/local #another subvolume

When installing the linux client, I picked the BTRFS snapshot option.

I am finding that I am unable to backup any of the nested sub volumes. If I choose the top backup directory to be ‘/’ then all of the directories where the nested volumes start are empty. If I chose one of the nested sub volumes as the top backup directory then the resulting backup is empty.

Should I be able to backup nested BTRFS sub volumes when using the BTRFS snapshot mechanism with UrBackup?

Cheers!

absolution · July 8, 2021, 1:07pm

I did manage to get this to work by manually mounting the Subvolumes. So, in fstab, I have something like

/dev/disk/by-uuid/9089df6a-b631-4121-9d48-5be65f41f642 / btrfs defaults,ssd,noatime,space_cache,commit=120,compress=zstd,subvol=@ 0 1
/dev/disk/by-uuid/9089df6a-b631-4121-9d48-5be65f41f642 /mnt/systemsubvols/home btrfs defaults,ssd,noatime,space_cache,commit=120,compress=zstd,subvol=@/home 0 1

Pointing UrBackup to --both-- paths as separate backup paths backs up both root and the home subvol.

uroni · July 8, 2021, 7:56pm

I guess this needs to be handled in

github.com

uroni/urbackup_backend/blob/dev/linux_snapshot/btrfs_create_filesystem_snapshot

#!/bin/bash

set -e

SNAP_ID=$1
SNAP_MOUNTPOINT="$2"
SNAP_NAME="$3"
SNAP_ORIG_PATH="$4"

CDIR=`dirname $0`
. $CDIR/filesystem_snapshot_common
exit_exclude_snapshot_mountpoints "$SNAP_MOUNTPOINT"

set_filesystem_type "${SNAP_MOUNTPOINT}"

if [[ $TYPE == "" ]]
then
        if btrfs subvolume list -o "$SNAP_MOUNTPOINT" > /dev/null 2>&1
        then
                TYPE="btrfs"

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and btrfs_remove_filesystem_snapshot. Changes for that would be welcome!