{
  "status": "shipping",
  "advantages": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-21",
  "slug": "protective-mbr",
  "term": "Protective MBR",
  "aliases": [
    "PMBR",
    "protective Master Boot Record"
  ],
  "definition": "A protective MBR is a legacy-format record at LBA 0 of a GPT disk that uses partition type 0xEE to discourage GPT-unaware tools from treating its space as unused.",
  "note": "The protective record starts at LBA 1 and describes the remaining disk, capped at 0xFFFFFFFF logical blocks when its size field cannot represent that span. It is a compatibility marker, not a duplicate list of the GPT partitions. [uefi]\n\nA recognizable 0xEE entry alone is not a complete GPT validation. Linux v6.18 treats protective-MBR checks separately from GPT header and entry-array checks. Preserve original acquisition bytes; partition repair belongs on a separate working copy. [linux]",
  "limitations": [
    {
      "text": "The marker cannot prevent arbitrary writes or substitute for an independent recovery copy.",
      "citationIds": [
        "uefi"
      ]
    }
  ],
  "related": [
    "guid-partition-table",
    "partition-type-guid",
    "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"
    }
  ],
  "provenance": [
    "UEFI 2.10 protective layout; no claim that all partition tools honor the marker."
  ]
}