Why The Size of My Partition is Maxed Out at 2 Terabyte and How to Get Over it

My 2-Terabyte hard drive is filling up so I bought a 3-Terabyte one to replace it. But when I put it in my computer and fired up Disk Management, I saw this:

Noticed that the available size for partitioning on Disk 1 in the screenshot above is maxed out at 2048GB with the rest of the available size sitting at a separate volume. Why is that?

That’s because the Basic disk mode on Windows is a MBR-based (Master Boot Record) storage that uses 32-bit of addresses and sizes stored in the partition table, which by calculation, the maximum size of a partition cannot exceed 2-Terabyte.

And overcoming this capacity limitation was one of the prime motivations for the development of the GPT, GUID Partition Table.

So it’s time to convert my 3-Terabyte disk from Basic to GPT. Simply right click the Disk 1 tab and choose “convert to GPT”. A couple seconds later, I’ve got a disk like this:

So why can’t we just use it for everything?

The advantages of using a GPT partitioning system is obvious:

• it allows up to 128 primary partitions while MBR-based disks only supports up to 4.
• it allows a much larger partition size that is greater than 2-Terabyte.
• it’s reliable because it provides redundancy by writing GPT header and partition table both at the beginning and at the end of the disk. So a damage at the sector 0 won’t destroy the whole disk.
• etc..

GPT disks can be used as storage volume on pretty much all Windows Operating Systems, from XP and above, both 32-bit and 64-bit. But be cautious when used as boot volume,

• first, you can only used it as boot volume on 64-bit edition of Windows starting at Windows Vista SP1, and
• it only works on systems that contain UEFI (Unified Extensible Firmware Interface) boot firmware.

Simply put, since the capacity of hard drive is getting bigger and bigger, it’s safe that we can partition our new hard drive as GTP from now on, as long as we don’t use it as a booting disk.

See more details about GTP on Windows systems from this FAQ by Microsoft.