windows can not be installed on this disk. This computer's hardware may not support booting to this disk. Ensure that the disk controller is enabled in the computer's BIOS menu

Hello all,

I am trying to install Server 2012 R2 Datacenter on Lenovo ThinkServer RD650 with AnyRAID 720ix setup as RAID 6 as a single "virtual volume" of just under 4 TB via USB DVD drive and I am getting the following error...

"windows can not be installed on this disk. This computer's hardware may not support booting to this disk. Ensure that the disk controller is enabled in the computer's BIOS menu"

Note that it can see the total volume but wants to break it into two partitions to keep it under or at 2TB.

Why exactly is this happening with a modern server and RAID controller?  Do I simply need to do this?....
https://www.youtube.com/watch?v=7sIfo9Mrafs

Or something more in the BIOS or RAID controller BIOS?  This latter thing I don't feel I should have to deal with on a modern server, but I digress.

Also, I was hoping the "Thinkserver Deployment Manager" --> Deployment and selecting Server 2012 R2 as the OS would create a configuration environment for this to "just work", but was unable to get the thing to see my USB DVD drive (for lack of its own internal CD drive and two USB ports)...ughh.  So it could not install from the Windows 2012 R2 DVD.

Anyone who has been through this and can remember the ritual they invoked to get this working, I will be greatly appreciative for your help and insight.  Thank you :-)