{
  "slug": "sector-slipping",
  "term": "Sector slipping",
  "aliases": [
    "Sector slip"
  ],
  "definition": "Sector slipping assigns successive logical blocks to successive usable physical sectors while omitting defective positions from the address sequence.",
  "note": "The 1997 drive manual lists slipping at format time separately from automatic reallocation and post-format reassignment. [seagate-barracuda9]\n\nThe Hoskins patent describes full-volume slipping and separate alternate-sector redirection for later defects. Its slip list translates logical addresses past excluded positions; it is a documented design, not evidence that every HDD uses that algorithm. [hoskins-slip]",
  "status": "unknown",
  "advantages": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-10",
  "limitations": [
    {
      "text": "Slipping is not restricted by definition to one track; the cited patent describes a full-volume design.",
      "citationIds": [
        "hoskins-slip"
      ]
    },
    {
      "text": "Formatted capacity depends on reserved spares and sector size in the documented 1997 drive configuration.",
      "citationIds": [
        "seagate-barracuda9"
      ]
    },
    {
      "text": "A remapping count alone does not determine access latency; the 1994 model needed layout and rotational-position information and omitted individual spared-sector effects.",
      "citationIds": [
        "ruemmler-layout"
      ]
    }
  ],
  "related": [
    "alternate-sector-remapping",
    "logical-block-address",
    "defect-skipping",
    "scsi-defect-list"
  ],
  "citations": [
    {
      "id": "seagate-barracuda9",
      "title": "Seagate Barracuda 9 Product Manual, 83329030 Rev. C (July 1997), sections 3.1 and 3.5, pp. 6-7",
      "url": "https://www.seagate.com/support/disc/manuals/scsi/29030c.pdf",
      "accessed": "2026-11-10"
    },
    {
      "id": "hoskins-slip",
      "title": "Edward Sean Hoskins, Full volume slip defect management in a disc drive, US 6,925,580 B2 (2005), description of Figures 7-17",
      "url": "https://patents.google.com/patent/US6925580B2/en",
      "accessed": "2026-11-10"
    },
    {
      "id": "ruemmler-layout",
      "title": "Ruemmler and Wilkes, An introduction to disk drive modeling (1994), Data layout and Conclusions, author PDF pp. 5 and 15",
      "url": "https://john.e-wilkes.com/papers/IEEEComputer.DiskModel.pdf",
      "accessed": "2026-11-10"
    }
  ],
  "provenance": [
    "Historical source synthesis; no drive measurement or claim of current firmware coverage. IBM 3340 within-record defect skipping is a different mechanism."
  ]
}