@Mediacowboy i think i have mine working using the unionfs plug in in omv
configure everything including omv
install the unionfs plug in
configure your drives, create a filesystem on each drive and mount them
in the unionfs tab create and add the drives you want to use as a pool
setup your share(s)
dont shutdown until you move the mount commnds from fstab
i moved them, had to re order the commands to fit the cli syntax
i added the following to the /etc/fc.local file above the part where it prints your i.p.
sudo mount -o defaults,nofail,user_xattr,noexec,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0,acl /dev/disk/by-label/disk1 /srv/dev-disk-by-label-disk1
sudo mount -o defaults,nofail,user_xattr,noexec,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0,acl /dev/disk/by-label/disk2 /srv/dev-disk-by-label-disk2
sudo mount -o defaults,nofail,user_xattr,noexec,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0,acl /dev/disk/by-label/disk3 /srv/dev-disk-by-label-disk3
sudo mount -o defaults,nofail,user_xattr,noexec,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0,acl /dev/disk/by-label/disk4 /srv/dev-disk-by-label-disk4
sudo mergerfs -o defaults,allow_other,cache.files=off,use_ino,category.create=eprand,minfreespace=4G,fsname=ufs:365821fb-30db-4a59-945a-55bfb60a5616 /srv/dev-disk-by-label-disk1:/srv/dev-disk-by-label-disk2:/srv/dev-disk-by-label-disk3:/srv/dev-disk-by-label-disk4 /srv/365821fb-30db-4a59-945a-55bfb60a5616
save and reboot
looks like the drives are unmounted correctly on shutdown also.
i have shutdown and rebooted a few times and it seems to be working
your setup may be different but use the fstab entries as a guide
Dave