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What is GPT

Description: GPT (Globally unique identifier) Partition Table controls the startup process of operating systems, newer hard drives, and motherboards.

GPT is the replacement for MBR. The GPT - G(lobally Unique Identifier) Partition Table - allows hard drives to partition and boot using a clearly defined scheme that does NOT have to reference the old cylinder information that was formerly stored in the BIOS. This is especially important for the new larger drives above 2TB so their proper capacity can be recorded and used by the operating system.

 This new partitioning scheme gives several advantages and a few of the main ones are listed below.

  1. The Globally Unique Identifier is a plain text 36 character Unicode name for the partition which makes it easy for any software to identify it directly without needing special translation between the BIOS and the Operating System.
  2. The Disks can grow up to 256TB per partition in Windows.
  3. The possible number of active partitions has grown from 4 to 128 primary partitions under windows (but is theoretically unlimited). It is possible for windows to access 32,768 TB of information on a single drive mechanism. (Which is just a bit more than the 128 kilobytes that were on the single sided - single density floppy drives in the 1980's).
  4. The specification for the GPT is clearly documented at
  5. UEFI is NOT required for a GPT formatted disk since all the information needed for the disk is contained in the format itself.
  6. Windows XP x64; Windows Server 2003 (64 Bit); Windows Server 2003 SP1: Windows Vista; Windows Server 2008 R2 and 2008; Windows 7 all support GPT.

Under Windows 7 a disk that is already formatted as MBR can be converted to GPT. This will destroy ALL DATA.

  1. Go to Disk Management (Start » right click over Computer and choose Manage, from the left column choose Disk Management).
  2. Locate the disk to be converted. Disk 1 or Disk 0 etc.
  3. Right click on each partition and click on "Delete Volume" until the whole disk is unallocated space.
  4. Right click on the disk to be converted and choose "Convert to GPT Disk" from the menu.
  5. The process will take just a few minutes. When finished it will be a blank drive ready to create new partitions on.
  6. Create the desired partitions
  7. Close disk management.