btrfs-sxbackup requires (but does not document) "ionice" on the target

[larsks]

I tried using btrfs-sxbackup to back up to a Synology diskstation device, but the command fails with:

ERROR source :: Command ['ssh', '-o', 'ServerAliveInterval=5', '-o', 'ServerAliveCountMax=3', 'backup@btrfs', 'ionice -c3 btrfs receive "/volume1/backups/madhatter/home/"'] failed with error code 127 (bash: ionice: command not found)

This was a surprise, because the README only says:

The following packages have to be available on both source and destination

• bash
• btrfs-progs

It would be nice if sxbackup would not use ionice by default; if folks want to run btrfs receive using ionice, they can use an ssh forced command to modify the btrfs receive command line.

[masc3d]

yes, README does not include standard packages like util-linux or coreutils which are provided by most distros.
in the past it has been seen that omitting ionice can cause heavy io stalling for other processes during backup.

I don't have synology to test this, as similar other problems could be expected down the road with a heavily modified distro like this. but you could fork your own version and modify it accordingly.

I would accept PR for this, when implemented properly (ionice should remain the default with an option to disable it)