Converting MBR to GPT during Windows Server 2012 Setup OR using more than 2TB of space on your server

Was recently tasked with setting up a number of Dell servers that had a large on board storage array (16TB RAID 6), but after Windows 2012 R2 was installed I noticed I only had 2TB of available space! I tried a number of things in the Disk Management snap-in, but nothing I would do would enlarge the partition. After some Googling, I realized that it was because my RAID volume was formatted as MBR, not GPT.

After more research I realized there was no way to modify the disk after an install and I had no option other than to repave the box (fortunately I hadn't done much on the install).

Below are the steps I used to convert the MBR to GPT, ready to install my OS.

1. Changed BIOS to UEFI (this took forever for me to figure out. UEFI is tied to GPT and even though when booting to BIOS, it will let you convert a disk to GPT, it won't stay that way during the install)
2. Start the Windows Server (or other OS) install, but get to a command line (in Server 2012, choose the option to repair an existing installation > command line)
3. Enter the following commands
1. DISKPART
2. LIST DISK
3. SELECT DISK 0 (make sure that's the disk you want to convert)
4. CLEAN
5. EXIT
6. DISKPART
7. LIST DISK
8. SELECT DISK 0
9. CONVERT GPT
10. EXIT
4. Proceed with your installation (for Windows Server, at this point, the installation window has disappeared. No worries, just cd .. up a directory, and then type setup.exe to start the setup again.

After this, you will be able to use all of your disk space. 

Resources;

http://www.howtogeek.com/193669/whats-the-difference-between-gpt-and-mbr-when-partitioning-a-drive/
http://technet.microsoft.com/en-us/library/cc738416(v=ws.10).aspx

Dell T610 on boot: "Invalid PCIe card found in Internal Storage slot. System halted"

We just shipped a Dell tower server on a pallet up to one of our offices, but when powered on, we did not get a happy message:

"Invalid PCIe card found in Internal Storage slot. System halted"

After starting to sweat a little thinking about how much time I had spent configuring this machine, I had one of our staff unseat the RAID card and then re-seat it. It booted right up. It must have just come loose during transit. A lesson to me, that even if it is a 70lb server and palletized, UPS/FedEx will still throw it around, so pack well!