{
  "slug": "interlaced-magnetic-recording",
  "term": "Interlaced magnetic recording",
  "aliases": [
    "IMR"
  ],
  "definition": "Interlaced magnetic recording alternates partially overlapping top and bottom tracks so that a bottom-track update can affect valid data on its two neighboring top tracks.",
  "note": "Top and bottom name overlapping track roles, not opposite platter surfaces. The studied layout permits a top-track update without the same neighbor-rewrite requirement. [wu]\n\nPreservation policy matters independently of the layout. IMRSim holds affected data in memory, whereas KVIMR describes an ordered backup-region and restore sequence. A count of neighboring tracks is therefore not a complete byte-write or durability contract. [imrsim] [kvimr]\n\nThe linked Hesela analysis separates disk reads from writes in six constructed examples. Its numbers are accounting results, not physical IMR observations or a reproduction of either system. [hesela-imr]",
  "status": "research",
  "advantages": [],
  "limitations": [
    {
      "text": "The reviewed simulation and CMR-backed emulation do not establish the performance or power-loss behavior of a commercial IMR drive.",
      "citationIds": [
        "wu",
        "kvimr",
        "imrsim"
      ]
    }
  ],
  "related": [
    "smr",
    "hamr",
    "hdd",
    "write-amplification",
    "hot-cold-data-separation"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-21",
  "citations": [
    {
      "id": "wu",
      "title": "Wu et al. Data Management Design for Interlaced Magnetic Recording. HotStorage 2018, sections 1-3.",
      "url": "https://www.usenix.org/system/files/conference/hotstorage18/hotstorage18-paper-wu.pdf",
      "accessed": "2026-10-21"
    },
    {
      "id": "kvimr",
      "title": "Liang, Yang and Yang. KVIMR. USENIX ATC 2021, sections 3.3-3.4 and 4.1.",
      "url": "https://www.usenix.org/system/files/atc21-liang.pdf",
      "accessed": "2026-10-21"
    },
    {
      "id": "imrsim",
      "title": "Zeng et al. IMRSim. arXiv:2206.14368v1, sections 2.1 and 3.",
      "url": "https://arxiv.org/pdf/2206.14368v1",
      "accessed": "2026-10-21"
    },
    {
      "id": "hesela-imr",
      "title": "Hesela: Interlaced recording, preservation policy and byte accounting",
      "url": "https://hesela.com/analyses/imr-track-overlap-write-accounting/",
      "accessed": "2026-10-21"
    }
  ],
  "provenance": [
    "Research-design record based on versioned papers. No contemporary product-availability survey, simulator execution, hardware measurement or crash-safety validation is claimed."
  ]
}