Using RAID on Optiplex

Hi Dell gurus,

I got few Dell Optiplex(75x,78x so on) desktops.
I want to install Linux/VMs on these desktops.
What I need from OS standpoint, I need to see multiple disk visibilities.
This means, I put 2 HDDs to Optiplex and build RAID(0 or 1), then install Linux.
When I login Linux, I want to see /dev/sdc, /dev/sdd, /dev/sde, /dev/sdf ....

I enabled RAID from System config, then I created Volume0 and Volume1(I can't create more than 2 volumes) from RAID config page when I started Optiplex.
When I logined after OS installation, I see just original HDDs /dev/sdb, /dev/sdc and 2 mapping devices /dev/map..(these the volumes I created from RAID page)
I installed OS on USB stick, so just want to utilize 2 HDDs for multiple additional devices.

I could see many 'segments' from Dell Optiplex User Guide on RAID part.
Is this concept(multiple /dev/sdx devices) possible?

Thanks,
ManyOptiplex