{
  "slug": "filesystem-consistency-invariant",
  "term": "Filesystem consistency invariant",
  "aliases": [
    "File-system consistency invariant"
  ],
  "definition": "A filesystem consistency invariant is a rule relating filesystem metadata that must hold at a defined consistency boundary.",
  "note": "Recon checked metadata relationships at transaction commit; this differs from validating a block checksum. Its 2012 evaluation was ext3-focused. The 2014 follow-up checked per-write location invariants as well, rather than assuming transactional writes were correct.",
  "status": "research",
  "advantages": [],
  "limitations": [
    {
      "text": "Coverage depends on the specified rules, observation point and implementation; it does not establish application-level correctness.",
      "citationIds": [
        "recon12",
        "recon14"
      ]
    }
  ],
  "related": [
    "checksum",
    "data-scrubbing",
    "crash-consistency",
    "write-ahead-log",
    "copy-on-write"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "recon12",
      "title": "Fryer et al. Recon: Verifying File System Consistency at Runtime. FAST 2012, sections 2, 4.1 and 5",
      "url": "https://www.usenix.org/legacy/events/fast/tech/full_papers/Fryer2-16-12.pdf",
      "accessed": "2026-10-13"
    },
    {
      "id": "recon14",
      "title": "Fryer et al. Checking the Integrity of Transactional Mechanisms. FAST 2014, sections 3.1 and 5",
      "url": "https://www.usenix.org/system/files/conference/fast14/fast14-paper_fryer.pdf",
      "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"
}