Datastore on NFS: "EINVAL: Invalid argument"

hupfdule

New Member
Nov 20, 2025
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Hello,

I am trying to configure PBS to use a datastore on NFS. It is an NFS server on a linux machine, not a NAS like in this post.

But the problem is the same. Trying to create the datastore leads to

# proxmox-backup-manager datastore create teststore /mnt/nfs-datastore
TASK ERROR: EINVAL: Invalid argument
Error: task failed (status EINVAL: Invalid argument)

The export is defined as

/media/backup/proxmox/pbs 192.168.178.0/24(rw,async,no_subtree_check,insecure,no_root_squash)

It is an external USB harddrive with an XFS partition.

I can mount it in PBS

mount -t nfs -o nfsvers=4 192.168.178.9:/media/backup/proxmox/pbs /mnt/nfs-datastore

and it has the correct permissions.

# ls -lhad /mnt/nfs-datastore/
drwxr-xr-x 2 backup backup 6 Nov 20 17:12 /mnt/nfs-datastore/

As root I can create a test file in it. I am not able to do this with the backup user...

# su - backup -c 'touch /mnt/nfs-datastore/testfile'
This account is currently not available.

Unfortunately the logfile doesn't reveal much more info about that problem.