My recommendation? Set onboard RAID/SATA to AHCI (don't use the Intel/S1x0 controller), then mirror the drives in Windows.
Hello.There is a Dell PowerEdge T30 (service tag: ). It is necessary to create the raid mirror (Raid 1), how to do it? I looked at the BIOS - "raid on" is worth it. With the set "raid on" I tried when loading ctrl + r, ctrl + i - I can not go into the raid configuration utility. Windows Server 2012 r2 (if relevant here). Please help 
PowerEdge T30 - how to create RAID 1?