I found OMV before some days an it's nice.
Debian with a web-based config engine.
I hate using the Thecus own system on my Thecus because it's too restricted.
During the installation of OMV I found some points I will later describe them all.
But first here: Why you are not creating the partitions as you want before you install?
For my system I wasn't able to boot after install, I think this is because of the system partition was more than 20GB.
Why it's not possible to do the partitioning during installation?
Because of the file "\install\preseed.cfg".
I commented out the whole block after
# This makes partman automatically partition without confirmation.
and was able then to do the partman steps as I want:
Device Size Used Free Use% Mountpoint
/dev/sda1 479M 39M 415M 9% /boot
/dev/sda2 6,1G 1,1G 4,7G 19% /
/dev/sda3 23G 45M 22G 1% /home
Yes, i have no swap, I think, 2 x 2GB of Ram should be enough for a NAS server.
Regards from Germay