Setup a new build of OMV due to issues with the gui. Disconnected all drives apart from the installation disk, reinstalled OMV, put back in disks and rebooted. Everything seemed to work fine, reconfigured everything and left it over night.
Came to it this morning and one of the disks is not showing up in OMV (under "Physical Disks"), in the Filesystems tab the file system is there but it says 'missing'. If login in through ssh and goto the mount its partially there. I can create files / directories on the disks without issues.
Not sure what other information to provide, anyone know where I could start to debug this?