{
  "slug": "draid",
  "term": "dRAID (OpenZFS)",
  "aliases": [
    "OpenZFS dRAID",
    "distributed RAID"
  ],
  "definition": "OpenZFS dRAID is a RAID-Z variant with fixed-width redundancy groups distributed across child devices and integrated distributed-spare capacity.",
  "note": "OpenZFS 2.3 spreads reconstruction work across children instead of funneling writes into one spare disk. Its fixed-width layout permits sequential resilvering but pads small blocks; eight data columns with 4 KiB sectors have a 32 KiB minimum allocation. Configured distributed spares serve only their own dRAID vdev. [zconcepts23]\n\nSequential reconstruction restores redundancy without verifying checksums and is followed by a scrub. That is a separate verification stage, not a promise of file-level access beyond parity tolerance. D-GRAID is a different research design. [zreplace23] [dgraid04]",
  "status": "shipping",
  "limitations": [
    {
      "text": "Fixed-width padding can reduce usable capacity and effective compression for small blocks.",
      "citationIds": [
        "zconcepts23"
      ]
    },
    {
      "text": "Distributed spare capacity is a recovery resource, not extra parity.",
      "citationIds": [
        "zconcepts23"
      ]
    }
  ],
  "related": [
    "raidz",
    "parity-declustering",
    "distributed-spare",
    "resilver",
    "d-graid"
  ],
  "citations": [
    {
      "id": "zconcepts23",
      "title": "OpenZFS 2.3 zpoolconcepts(7): dRAID virtual devices and hot spares.",
      "url": "https://openzfs.github.io/openzfs-docs/man/v2.3/7/zpoolconcepts.7.html",
      "accessed": "2026-11-09"
    },
    {
      "id": "zreplace23",
      "title": "OpenZFS 2.3 zpool-replace(8): sequential reconstruction and subsequent scrub.",
      "url": "https://openzfs.github.io/openzfs-docs/man/v2.3/8/zpool-replace.8.html",
      "accessed": "2026-11-09"
    },
    {
      "id": "dgraid04",
      "title": "Sivathanu, Prabhakaran, A. C. Arpaci-Dusseau and R. H. Arpaci-Dusseau. Improving Storage System Availability with D-GRAID. FAST 2004, sections 3, 5-7 and 9.",
      "url": "https://www.usenix.org/legacy/events/fast04/tech/sivathanu/sivathanu.pdf",
      "accessed": "2026-11-09"
    },
    {
      "id": "hesela-rebuild",
      "title": "Hesela: partial file availability, dRAID and recovery milestones",
      "url": "https://hesela.com/analyses/raid-rebuild-ure-math-and-resilver/#dgraid-availability",
      "accessed": "2026-11-09"
    }
  ],
  "advantages": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-09"
}