On June 29th Synology finally released a new major version of their flagship NAS OS DiskStation Manager for all supported models. Fortunately enough, so I thought, my DS216j was on the list so why would I wait...

Upgrade was smooth, took few minutes plus a reboot and boom, here's my shiny one!

Bad luck came just few days later when I noticed there's something off with my backup and one of the VMs was throwing error when the job was running. Quickly and to my horror I found that vCenter NFS datastore is now reading as inaccessible. There was no change on the vCenter end done so I quickly ran to the DSM to see what's up. So here's what's up...

Yeah, despite official manual saying you can still enable NFS 4.1 it looks like I am left only with v4 and no option to use that specific version in the vCenter.

I probably should be more careful reading release notes because here's what I got there:

NFSv4.1 and related advanced functions (multipathing) are no longer supported on Synology NAS models with the following package architectures: Alpine, Alpine4k, armada38x, Avoton, Braswell, Bromolow, Cedarview, Grantley, Monaco. If you had previously enabled NFSv4 and NFSv4.1, the maximum NFS protocol is set to NFSv4 by default after the update.

DS216j got Marvell Armada 385 88F6820 processor onboard so it clearly fall into armada38x line, sadly.

Well, am I lost then? Not quite. Seems that there is an option to get that feature back regardless of that, honestly nasty, move.

Let's get into the fix part real quick.

First, SSH to the NAS. Then edit /etc/nfs/syno_nfs_conf and change it to following:

udp_read_size=32768
udp_write_size=32768
nfsv4_enable=yes
nfs_unix_pri_enable=1
nfs_custom_port_enable=no
statd_port=0
nlm_port=0
nfs_minor_ver_enable=1

Note two bolded lines, first nfsv4_enable=yes keeps NFS4 enabled (basically same as GUI switch), second, the king and the savior nfs_minor_ver_enable set to 1 enables NFS4.1 support regardless it's gone from GUI.

Make sure you got that part changed! Then save the file and run systemctl restart nfs-server and NFS4.1 is back in business.

Just to make sure it stays this way after any upcoming update I added immutability flag to the syno_nfs_conf file.

Of course there must be a but to the case... If you now go to the GUI and check available NFS options for whatever reason DSM will claim Maximum NFS protocol is NFSv3 (there's no v4 to choose).

That's something I can accept.

Until next time!