If you have a Linux VM configured with the ZFS file system, the traditional snapshot-based backup won't be able to capture data contained in the machine.
The ZFS file system is a particular advanced file system available in some Linux distributions that can be tricky to backup due to its nature.
The ZFS file system cannot be backed up with traditional snapshots therefore most of backup solutions based on snapshot technology may result unable to process this type of FS. If you try performing a file-level restore of a ZFS VM, the ZFS partition will result empty.
Veeam how to backup ZFS file system
Because ZFS is not supported by snapshot-based backup, you need a specific backup configuration to process data that resides in a file system mounted to the root file system of the machine. To backup these machines you need to use the Veeam Agent for Linux configured to create file-level backup in the snapshot-less mode.
Snapshot-less mode is an option available in the Veeam Agent file-level backup job properties that doesn't create a snapshot of the backed up volume but reads files and directories selected to backup and then copies data to the target backup repository.
This article has been written for StarWind blog and can be found in this page. It covers the full procedure to backup ZFS file system in Veeam.
Test backup
Using the snapshot-less mode, the ZFS file system has been processed successfully and you are now able to restore the requested files.
Although ZFS file system is not massively used in VMs, you may need to backup some servers running this file system. Snapshot-less is the option you need to use for a successfull backup.
Read the full article on StarWind blog.
