GPT is required for drive sizes larger than 2TB. Below is an example setup where we created a virtual RAID5 array with 2.8TB
1) Setup Raid 5 in bios of 9279 8i when booting system. This will get you 2.8TB. drive
2) Load 2012 windows cd and go to drive setup screen.
3) Hit shift f10 and use DISKPART command to CONVERT DISK GPT. LIST DISK to make sure it is GPT.
4) Hit reset switch and set first boot priority to uefi cd/dvd rom and reboot to 2012 server cd.
5) At 2012 server setup disk screen, should see 2.8TB hard disk. Try to install on this volume. Windows will create 4 partitions but will not allow you to install on fourth and largest partition (2.8TB).
6) Hit reset switch and set boot priority to 1st—uefi hard disk, 2nd ----to uefi cd/dvd rom and reboot system with Server 2012 dvd again.
7) This time you will see 4 partitions again, but now Server 2012 setup will allow you to install the software on the 4th and largest partition which is what you want. After install do not change boot options and MS Server 2012 works perfectly and you will see 3 partitions under Disk Management. The recovery partition will be hidden.