I have a Dell R620 with 3tb of disk on a Raid5. When I try to install win 2012 .. it does not partition the disk properly.. Essentially I am trying to give os partitioin 400gb and rest needs to be on a single partition of 2.6TB. I know its an issue with GPT.. I am not sure how to configure it so when I boot off the usb drive win 2012 setup installs it as a GPT.
On the bios I have it setup as uefi.. not sure if it needs to be on bios.