so far I managed to get the system boot from USB Stick, DATA Mirror RAID with two HDs....runs perfekt so far.
I installed two aditional disks, formatted ext4. I installed the LMV plugin.
Now, as I go into the Logical Volume Management and try to add a Physical Volume.....there is nothing to select
Same behavior in OMV 5 and OMV 4.1
Thanks for help!