Actually the question should be, what are proper steps to do?
I'm asking because in the past i have done several times in bad way before and therefor left many dead hyperlinks and on the end system disk failure of OMV(reinstall).
There are two hard drives and next are places where they are :
-Storage:
1. Union Filesystems (Merged in one whole by)
2. File systems(two hard drives separately and as one whole)
3. S.m.a.r.t. --> Scheduled tests
-Access Rights Management
4.User? There is another(3th) hdd in use
5.Shared Folders
-Services
6.Apple Filing --> Shares
7.DLNA --> MiniDLNA --> Shares
8.NFS --> Shares
If possible by numbers steps to describe.