Which RAID controller are the drives connected to? Server 2012 R2 should have drivers for all the RAID controllers in a T420 except the S110. Also know that the H710 REQUIRES RAID to be configured and initialized BEFORE Windows can see any disks (it does NOT support non-RAID).
Hello, I have a PowerEdge T420 that I am attempting to install Win2012 R2 on - totally blank, not had an OS yet.  During the install phase, Windows can't find the Hard Drives to target.  This is expected, and I've seen it on other systems before.  The solution has been to provide the drivers for the Raid controller within, which then allows me to set up the install. Unfortunately, I've tried every "Driver" entry under SAS RAID on this list:www.dell.com/.../drivers But unfortunately none of them are up to scratch:  Each time I load the CD with them, the installer claims there are no signed drivers on the disk. So what do I do next?  It is a T420, and all the bays do have drives, and they are intended to be a RAID.  Not sure what else to do. Thanks, M.  EDIT:  I have also tried the "Drivers for OS Deployment".  No luck.
T420 Raid Driver Questions