OMV without nfs v4 server

Why does OMV only support NFS v3 on server side?

As a client i can connect to other nfs shares as v4 and OMV client side has that option in the settings but despite client asking for v4, the OMV server only connects as v3.

On the server and client side I can see that nfs v4 it is available

root@rpi42:~#  cat /proc/fs/nfsd/versions
-2 +3 +4 +4.1 +4.2
root@raspberrypi:~# cat /proc/fs/nfsd/versions
-2 +3 +4 +4.1 +4.2

The server also generated this OMV file in /etc/exports which defines nfs v4 features

# This file is auto-generated by openmediavault (https://www.openmediavault.org)
# WARNING: Do not edit this file, your changes will get lost.

# /etc/exports: the access control list for filesystems which may be exported
#               to NFS clients.  See exports(5).
/export/xxx x.x.x.x(fsid=ef31fe51-96f1-479a-b813-fac58204e83b,rw,subtree_check,insecure)
/export/aa x.x.x.x(fsid=d31e5fc1-de32-407f-957c-3a57c3792009,rw,subtree_check,insecure,no_root_squas>
/export/bb x.x.x.x (fsid=9b0de405-7404-4449-b56d-6462d5970e8b,ro,subtree_check,insecure)
/export/cc x.x.x.x(fsid=0bba89b0-8e9c-42c1-afee-361824beb918,ro,subtree_check,insecure)
/export/NFS_test 192.168.9.1/24(fsid=862bc1e6-b665-42fa-b1b1-e7740bdd81b0,rw,no_subtree_check,async,no_root_squash)

# NFSv4 - pseudo filesystem root
/export x.x.x.x (ro,fsid=0,root_squash,no_subtree_check,hide)
/export x.x.x.x (ro,fsid=0,root_squash,no_subtree_check,hide)
/export x.x.x.x(ro,fsid=0,root_squash,no_subtree_check,hide)

mounting nfs either in OMV Gui or manually show only v3

sudo mount -t nfs4 x.x.x.x:/export/NFS_test /srv/_testdir

after the client side "nfsstat -m" shows version 3: 

/srv/_testdir from x.x.x.x:/export/NFS_test
 Flags: rw,relatime,vers=3,rsize=524288,wsize=524288,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=x.x.x.x,mountvers=3,mountport=34991,mountproto=udp,local_lock=none,addr=x.x.x.x

>> So I followed the Debian Setup Wiki nfs setup for NFS4 only server and added the missing entries to the following files

/etc/default/nfs-common
/etc/default/nfs-kernel-server

This results in an error on client side

root@rpi42:/# mount -t nfs4 x.x.x.x:/export/NFS_test /srv/_testdir
mount.nfs4: requested NFS version or transport protocol is not supported

root@rpi42:/# mount -t nfs x.x.x.x:/export/NFS_test /srv/_testdir
mount.nfs4: requested NFS version or transport protocol is not supported

Unfortunately, I have no other ideas how to find solutions . And the issue is definitely on OMV/Debian side, as I have tried with non-OMV servers as nfs server, which can be connected to with v4.

Incredible. thanks Jeff001. That fixed it! Thank you very much!

The reason why I used the old convention is that OMV GUI is asking to do so (including export). I did not know that v4 required a different mount path and it seems strange that the server changes protocol version just because of a way to describe the access path, even though I explicitly ask vor v4 in the command. Anyway thanks for pointing this out.

Probably worth changing the wording in the OMV Plugin to correct that. Otherwise people will always connect as v3.

At votdev: This text in GUI should probably be changed to reflect the fact that for v4 to work, the share definition MUST NOT have a path (like ..export) included, otherwise the server will automoatically default to v3, and not even tell anybody about it

As jeff0001 kindly pointed out above, the def for v4 must only be server IP.

Also worth mentioning that the paramaters aparently make a big difference to performance. I have not verified this but its probably worth trying out for OMV users.

Benchmarking NFS v4 vs NFSv3

>>remotemounts in OMV_Extras