{
  "slug": "opportunistic-scrubbing",
  "term": "Opportunistic scrubbing",
  "aliases": [],
  "definition": "Opportunistic scrubbing uses ordinary storage accesses as opportunities to verify regions whose inspection age has exceeded a target.",
  "note": "The MASCOTS 2004 archive model attaches overdue-region checks to disk accesses to avoid separate power-ups; infrequent accesses require a periodic fallback. Its reliability results are model-dependent, not measurements of current drives. [schwarz04]\n\nA target is not evidence of completed coverage. In Hesela's explicit single-region trace, a 14-day threshold produces its first check on day 29; the model assumes instantaneous successful checks and uses a strict greater-than trigger. It is not a reproduction of the paper's simulator. [hesela-trace]\n\nIn that paper, the opportunity is a disk access, while the inspection clock belongs to each disk portion. An access can trigger checks of overdue portions other than the requested data; the access itself is not proof of their verification. [schwarz04]",
  "status": "research",
  "advantages": [],
  "limitations": [
    {
      "text": "Without an independent fallback or a bound on access gaps, access-only triggering does not bound inspection age.",
      "citationIds": [
        "hesela-trace"
      ]
    }
  ],
  "related": [
    "data-scrubbing",
    "adaptive-scrubbing",
    "inspection-paradox",
    "mean-time-to-detection"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-05",
  "citations": [
    {
      "id": "schwarz04",
      "title": "Schwarz, Xin, Miller, Long, Hospodor and Ng. Disk Scrubbing in Large Archival Storage Systems. MASCOTS 2004, pp. 409-418, sections 4.3 and 7.3.",
      "url": "https://www.crss.us/media/pubs/d0a1a0161119593cfdb6235492f689bdf8c79b76.pdf",
      "accessed": "2026-11-05"
    },
    {
      "id": "hesela-trace",
      "title": "Hesela: an opportunistic target is not a deadline, executable synthetic trace and limitations.",
      "url": "https://hesela.com/analyses/scrubbing-detection-not-durability/#opportunistic-scrubbing",
      "accessed": "2026-11-05"
    }
  ]
}