I've finished a storage migration on my 2 OMV5 instances (VMs under Proxmox with pass-through disks) from various RAID flavors on several 2TB HDDs to few un-mirrored SSDs.
0.- Update OMV to latest
1.- Attach SSD to the OMV VM
2.- Wipe the SSD
3.- Encrypt the SSD (this was is an extra step)
4.- Create a single filesystem on the SSD
5.- Initial copy (using rsync CLI) of the content of shared folders from different FS (RAIDs) to the new FS (SSD) (pass#1)
6.- Stop all clients, and reboot OMV5 VM
7.- Update copy (using rsync CLI) of the content of shared folders from different FS (RAIDs) to the new FS (SSD) (pass#2)
8.- Move the Shared Folders using the GUI from old FS to the new one.
9.- Stop/Start services (CIFS/NFS/RSYNC) or reboot
10.- Restart clients
11.- Delete & umount old FS, delete/wipe old disks & detach HDD from the VM.
Everything went smoothly with a very little downtime on clients (steps 6 - 10) but each time I've moved shared folders with NFS share (all went OK for CIFS/rsync/FTP only shared folders) it didn't reconfigure NFS correctly. In fact, the bind mounts under /export in /etc/fstab were not rewritten with the new FS mount point after the move + config update. I've not moved the shared folders all at the same time but one after the other applying config each time.
As I'm not salt expert, I ended by removing each NFS share, checking that the bind mount was removed in fstab before recreating the share -> valid fstab config.
So I guess there's a bug/missing action when moving a shared folder with NFS share configured from one FS to another in the GUI.