{
  "slug": "btrfs-nodatasum",
  "term": "Btrfs NODATASUM",
  "aliases": [
    "NODATASUM",
    "Btrfs no-data-checksum flag"
  ],
  "definition": "Btrfs NODATASUM marks file data as excluded from the filesystem's data checksumming.",
  "note": "NODATACOW implies NODATASUM, but disabling data checksums is not synonymous with disabling copy-on-write; the mount option applies to newly created files. Metadata remains checksummed.",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "Scrub cannot checksum-validate the affected file data or use those missing checksums to select a correct mirror after silent damage.",
      "citationIds": [
        "btrfs-scrub"
      ]
    }
  ],
  "related": [
    "data-scrubbing",
    "checksum",
    "copy-on-write",
    "mirroring"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "btrfs-mount",
      "title": "Btrfs documentation: btrfs(5), datacow/nodatacow and datasum/nodatasum",
      "url": "https://btrfs.readthedocs.io/en/latest/btrfs-man5.html",
      "accessed": "2026-10-13"
    },
    {
      "id": "btrfs-scrub",
      "title": "Btrfs documentation: btrfs-scrub(8), checksum exclusions and read-only limitations",
      "url": "https://btrfs.readthedocs.io/en/latest/btrfs-scrub.html",
      "accessed": "2026-10-13"
    },
    {
      "id": "btrfs-dedup",
      "title": "Btrfs documentation: Deduplication, compatibility of COW files with NODATASUM",
      "url": "https://btrfs.readthedocs.io/en/latest/Deduplication.html",
      "accessed": "2026-10-13"
    },
    {
      "id": "hesela-scrub",
      "title": "Hesela: Disk scrubbing, checksum coverage and consistency boundaries",
      "url": "https://hesela.com/analyses/scrubbing-detection-not-durability/",
      "accessed": "2026-10-13"
    }
  ],
  "updated": "2026-10-13"
}