Convert 3TB+ Disk to GPT in Windows

Problem

Convert a 3TB or larger drive from MBR to GPT (GUID Partition Table) so Windows can recognize its full capacity.

tl;dr

C:\> diskpart
list disk
select disk 2
clean
convert gpt
create partition primary
select partition 1
format fs=ntfs quick

Solution

Unfortunately, Windows has trouble reading disks larger than 2 terabytes in size. The reason for this, is that Windows typically stores the disk partition table in the disk's MBR (Master Boot Record). A partition table is literally a map telling an OS what the partitions are, and where they are located, so the OS knows where it can read or write data.

Therefore, if you add a new drive to Windows (or you are installing an OS from scratch), you need to convert the disk to GPT. This can be accomplished via diskpart, a command-line disk partitioning tool. A basic guide on how to format a disk viadiskpart can be found here: Manually Format a Disk/Partition (Windows).

Then, you will wipe and partition the disk as usual, while adding a key command: convert gpt. This configures the selected disk to use GUID partition table.

First, start diskpart from command prompt, PowerShell, or recovery console:

diskpart

Then, select the disk you need to format:

list disk
select disk 2

Clean it and convert it to GPT:

clean
convert gpt

Finally, create a partition as normal:

create partition primary
select partition 1
format fs=ntfs quick

You are now done, and Windows will have no issues recognizing the full 3 TB or more on the disk. You can install Windows to the disk as well.

Convert disk to GPT during Windows installation

If you are installing Windows to a clean hard drive larger than 2TB, you need to boot into your installation media (DVD, USB stick, etc) via the UEFI mode. This can be done by invoking the Boot Menu (usually by mashing the F8 key when your server or computer starts up). Then, when you are at the disk selection screen during Windows installation, hit Shift-F10 to open the command prompt. You do not need to format the disk through the command line, however you may need to clean and convert it. Once there, follow the same set of steps as before:

diskpart
list disk
select disk 0
clean
convert gpt
exit


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