{
  "status": "shipping",
  "advantages": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-21",
  "slug": "guid-partition-table",
  "term": "GUID Partition Table (GPT)",
  "aliases": [
    "GPT",
    "GUID partition table"
  ],
  "definition": "GUID Partition Table is a disk-partitioning format that records partition ranges and identifiers in primary and backup metadata with separate CRC32 checks for the headers and entry arrays.",
  "note": "GPT describes disk layout, not a filesystem. A protective MBR occupies LBA 0, the primary header LBA 1 and the backup header the final logical block. Partition ranges use logical block addresses; converting them to byte offsets requires the correct logical block size. [uefi]\n\nA passing header CRC does not establish that the referenced entry array passes its own CRC. Neither covers partition payload. Linux v6.18 separately checks the header and array, then compares selected metadata between copies; these checks do not prove that recovered files are complete or current. [linux]\n\nIn Hesela's six constructed regular-file cases, all 24 invocations of sfdisk 2.39.3 and sgdisk 1.0.10 returned zero, including commands that warned about primary corruption or inconsistent copies. A partition listing or successful process exit does not certify both original copies: retain stdout, stderr, selected-copy behavior and independent byte checks. The exact package versions and hashes are recorded with the observations. [native]",
  "limitations": [
    {
      "text": "With a 92-byte header, the remaining reserved header-block bytes are outside the header CRC, although UEFI requires them to be zero; CRC success is not full format conformance.",
      "citationIds": [
        "uefi"
      ]
    },
    {
      "text": "Backup partition metadata is not a backup of the files described by it.",
      "citationIds": [
        "uefi"
      ]
    },
    {
      "text": "CRC checks do not authenticate the metadata or establish which of two inconsistent copies is newer.",
      "citationIds": [
        "uefi",
        "linux"
      ]
    }
  ],
  "related": [
    "protective-mbr",
    "partition-type-guid",
    "partition-alignment",
    "logical-sector",
    "checksum",
    "ddrescue-mapfile"
  ],
  "citations": [
    {
      "id": "uefi",
      "title": "UEFI 2.10, chapter 5: GPT layout, headers and partition entries",
      "url": "https://uefi.org/specs/UEFI/2.10/05_GUID_Partition_Table_Format.html",
      "accessed": "2026-10-21"
    },
    {
      "id": "linux",
      "title": "Linux v6.18 GPT parsing: is_gpt_valid and compare_gpts",
      "url": "https://raw.githubusercontent.com/torvalds/linux/v6.18/block/partitions/efi.c",
      "accessed": "2026-10-21"
    },
    {
      "id": "native",
      "title": "Hesela: 24 native GPT parser observations, method and version scope",
      "url": "https://hesela.com/analyses/ddrescue-image-provenance/#gpt-parser-observations",
      "accessed": "2026-10-21"
    }
  ],
  "provenance": [
    "Format explanation and version-pinned parser source review; no firmware or damaged-drive recovery test.",
    "Six deliberate synthetic GPT files exercised by four read-only commands in one installed environment; not firmware, boot, kernel-parser, repair or damaged-drive testing."
  ]
}