EMZETT.GPT (GUID Partition Table)
In short: GPT is the modern partitioning scheme for disks. Each partition receives a worldwide unique identifier (GUID). GPT replaces the old MBR and belongs to UEFI.
In more detail: A partition table defines how a disk is divided into areas (partitions). GPT stores it at the beginning and the end of the drive, which makes it more robust against damage. It contains checksums (CRC) to detect errors.
In Depth
Structure of a GPT disk:
LBA 0 : protective MBR (so old tools do not consider the disk empty)
LBA 1 : GPT header
LBA 2…33: partition entries (up to 128, 128 bytes each)
… : the partitions
End : backup copy of table and header
| MBR | GPT | |
|---|---|---|
| Maximum disk size | 2 TiB | about 9.4 ZB (with 512-byte sectors) |
| Primary partitions | 4 (or 3 + extended) | 128 (in Windows) |
| Identifier | simple type byte | 128-bit GUID per partition and type |
| Backup of table | none | copy at the end |
| Error detection | none | CRC32 |
| Boot | BIOS / legacy | UEFI (a BIOS with add-on can too) |
- GUID: “Globally unique identifier”, a 128-bit number like
C12A7328-F81F-11D2-BA4B-00A0C93EC93B(type GUID of the EFI system partition). Thanks to its length practically unique. - Typical partitions under Windows 11: EFI system partition (ESP, about 100 to 260 MB), Microsoft reserved partition (16 MB), Windows partition (C:), recovery partition.
- Converting:
mbr2gpt /validateand/convertconvert the system disk from MBR to GPT without data loss. Afterwards the firmware must start in UEFI mode. - Showing:
diskpart→list disk(column “GPT” with asterisk), or Disk Management. - Backup: A damaged table can often be restored from the copy at the end of the disk (tools: gdisk, TestDisk).
See also: MBR (Master Boot Record), Partitions, EFI system partition and system partition