# /etc/fstab: static file system information.
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
# <file system> <mount point> <type> <options> <dump> <pass>
# / was on /dev/sdb1 during installation
UUID=7f0aace4-fe71-4f1f-8dc1-a11a3a778d2e / ext4 errors=remount-ro 0 1
# swap was on /dev/sdb5 during installation
UUID=e92c95d2-ab6c-4c6e-a9bd-41a2fbc954df none swap sw 0 0
tmpfs /tmp tmpfs defaults 0 0
# >>> [openmediavault]
/dev/disk/by-label/IronWolf1 /srv/dev-disk-by-label-IronWolf1 btrfs defaults,nofail 0 2
/dev/disk/by-label/4TBHDD /srv/dev-disk-by-label-4TBHDD btrfs defaults,nofail 0 2
/dev/disk/by-label/Samsung1TB /srv/dev-disk-by-label-Samsung1TB btrfs defaults,nofail 0 2
/dev/disk/by-label/IronWolf2 /srv/dev-disk-by-label-IronWolf2 btrfs defaults,nofail 0 2
/dev/disk/by-label/IronWolf3 /srv/dev-disk-by-label-IronWolf3 btrfs defaults,nofail 0 2
/dev/disk/by-id/ata-KINGSTON_SH100S3120G_50026B721A111383-part3 /srv/dev-disk-by-id-ata-KINGSTON_SH100S3120G_50026B721A111383-part3 ext4 defaults,exec,nofail,user_xattr,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0,discard,acl 0 2
/srv/dev-disk-by-label-4TBHDD:/srv/dev-disk-by-label-Samsung1TB:/srv/dev-disk-by-label-IronWolf2:/srv/dev-disk-by-label-IronWolf3 /srv/512e1b65-7039-44af-a2ff-5e2d6a0661f2 fuse.mergerfs defaults,allow_other,direct_io,use_ino,category.create=mfs,minfreespace=4G 0 0
/srv/dev-disk-by-id-ata-KINGSTON_SH100S3120G_50026B721A111383-part3/ /var/lib/docker/openmediavault none bind,defaults,exec 0 0
# <<< [openmediavault]
Just a heads up that any changes made to fstab that fall between the [openmediavault] tags will get reset by the OS on certain events. I had this issue recently as well. So, Plex may work well now, but in a day or two you'll find that transcoding has stopped again.
See my thread here where this was answered by @gderf himself. I apologize if this was answered later in this thread, I didn't notice it as I skimmed through.