GPT (an acronym for “GUID partition table”) a disk-partitioning scheme that is used by the Extensible Firmware Interface (EFI) in Itanium-based computers. GPT offers more advantages than master boot record (MBR) partitioning because it allows up to 128 partitions per disk, provides support for volumes up to 18 exabytes in size, allows primary and backup partition tables for redundancy, and supports unique disk and partition IDs (GUIDs).
Unlike MBR partitioned disks, data critical to platform operation is located in partitions instead of unpartitioned or hidden sectors. In addition, GPT partitioned disks have redundant primary and backup partition tables for improved partition data structure integrity.
You can perform the same tasks on GPT disks as you can on MBR disks with the following exceptions:
- The operating system loader and boot partition must reside on a GPT disk. Other hard disks can be either MBR or GPT.
- You can have both MBR and GPT disks in a single dynamic disk group. You can also have a mix of basic GPT and MBR disks, which are not part of disk groups.
- You can convert an MBR disk to a GPT disk and vice versa only if the disk is empty.
- You cannot use the GPT partitioning style on removable media, detachable disks that use universal serial bus (USB) or IEEE 1394 (also called FireWire) interfaces, or on cluster disks that are connected to shared SCSI or Fibre Channel buses used by the Cluster service.