Hi,
This issue doesn’t appear to be related to Proxmox Backup Server or the NAS.
On the affected node, the containers have an extra data folder attached. During backup, Proxmox tries to include that folder, but it’s not available at the moment...
This is a TOML limitation, not a ZFS one.
In TOML, the same key cannot be used more than once, so this fails:
filter.ID_SERIAL "*194K"
filter.ID_SERIAL "*191V"
Use an array for filter.ID_SERIAL:
[disk-setup]
filesystem = "zfs"
zfs.raid =...