{
  "slug": "mean-time-to-data-loss",
  "term": "Mean time to data loss (MTTDL)",
  "aliases": [
    "MTTDL"
  ],
  "definition": "Mean time to data loss (MTTDL) is the expected time until a storage system first loses data that cannot be retrieved or reconstructed.",
  "note": "MTTDL integrates the no-loss survival probability over an unbounded horizon; it is not a finite-mission loss probability or a measure of loss size. [greenan-hotstorage10-pdf]",
  "related": [
    "normalized-magnitude-data-loss",
    "failure-domain",
    "erasure-coding",
    "mtbf"
  ],
  "status": "research",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-15",
  "citations": [
    {
      "id": "greenan-hotstorage10-pdf",
      "title": "Mean time to meaningless: MTTDL, Markov models, and storage system reliability, Greenan, Plank, and Wylie, USENIX HotStorage 2010 (USENIX PDF, independent academic source)",
      "url": "https://www.usenix.org/legacy/event/hotstorage10/tech/full_papers/Greenan.pdf",
      "accessed": "2026-10-15"
    },
    {
      "id": "hesela-durability",
      "title": "Eleven nines: what a durability model does not prove",
      "url": "https://hesela.com/analyses/s3-durability-eleven-nines-derivation/",
      "accessed": "2026-10-15"
    }
  ]
}