{
  "status": "shipping",
  "advantages": [
    {
      "text": "No separate journal device is required.",
      "citationIds": [
        "ppl"
      ]
    }
  ],
  "limitations": [
    {
      "text": "Does not guarantee preservation of in-flight data; loss of a modified member is outside that protection.",
      "citationIds": [
        "ppl"
      ]
    },
    {
      "text": "The documented Linux MD implementation does not combine PPL with a write-intent bitmap.",
      "citationIds": [
        "ppl"
      ]
    }
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "slug": "partial-parity-log",
  "term": "Partial Parity Log",
  "aliases": [
    "PPL"
  ],
  "definition": "Partial Parity Log is a Linux MD RAID5 mechanism that records the XOR of untouched stripe chunks before dispatching data and parity updates.",
  "note": "The log resides on the stripe's parity member. Its recovery scope is narrower than a data journal.",
  "related": [
    "raid-write-hole",
    "raid-5",
    "parity-raid",
    "write-intent-bitmap"
  ],
  "citations": [
    {
      "id": "ppl",
      "title": "Linux v6.12: Partial Parity Log",
      "url": "https://github.com/torvalds/linux/blob/v6.12/Documentation/driver-api/md/raid5-ppl.rst",
      "accessed": "2026-10-11"
    },
    {
      "id": "hesela-raid",
      "title": "Hesela: RAID write hole, bitmap and PPL",
      "url": "https://hesela.com/analyses/raid-write-hole-bitmap-ppl/",
      "accessed": "2026-10-11"
    }
  ]
}