How does PBS backup ensure point-in-time consistent filesystems and ZVOL states?

[carsten2]

How does the proxmox backup client ensure a point-in-time-consistent backup? From the backup client syntax I only see that a filesystem or image (no snapshot) is specified, which does not ensure that the filesystem is not changed during backup. This could lead to an inconsistent backup.

 

[dcsapak]

for backups of pve ct/vm see the reference documentation for backups https://pve.proxmox.com/wiki/Backup_and_Restore
especially the modes (stop/suspend/snapshot)

for 'host' backups, there is no consistency check and the admin has to ensure that it is ok (like when you use rsync for example)

 

[carsten2]

If snapshot mode for containers is used, how does the backup client access the snapshot (via the hidden .zfs directory?).
Is it possible to specifiy this for host backups also?

 

[dcsapak]

via the hidden .zfs directory?

no the snapshot subvolumes get mounted by us and we sync from there

Is it possible to specifiy this for host backups also?

since you have to script/schedule the call yourself anyway at the moment, you can simply include that
in the proxmox-backup-client call

e.g.

* make zfs snapshot
* mount it somewhere
* call proxmox-backup-client
* unmount the snapshot
* delete snapshot