{
  "slug": "borg-block-reorganization",
  "term": "BORG block reorganization",
  "aliases": [
    "BORG",
    "Block-reORGanization"
  ],
  "definition": "BORG is a research block-layer system that adapts HDD data placement to observed access sequences.",
  "note": "A dedicated on-disk target holds selected copies; an indirection map tracks their current location. Its write buffer collects writes. [borg09]\n\nALIS instead evaluates heat and repeated-run clustering with trace-driven simulation; its design can keep multiple reorganized copies of a block. [alis03]\n\nThe author project page does not offer a BORG code release and points to EXCES as a reference, not the same implementation. [borg-project]",
  "status": "research",
  "advantages": [],
  "limitations": [
    {
      "text": "An unstable read working set can make BORG slower; reorganizing blocks also consumes I/O.",
      "citationIds": [
        "borg09"
      ]
    }
  ],
  "related": [
    "diskseen",
    "table-based-prefetching",
    "readahead",
    "filesystem-defragmentation"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-13",
  "citations": [
    {
      "id": "borg09",
      "label": "BORG, FAST 2009",
      "title": "Bhadkamkar et al. BORG: Block-reORGanization for Self-optimizing Storage Systems. FAST 2009, sections 3-6 and 9.",
      "url": "https://www.usenix.org/legacy/event/fast09/tech/full_papers/bhadkamkar/bhadkamkar.pdf",
      "accessed": "2026-11-13"
    },
    {
      "id": "alis03",
      "label": "ALIS, Berkeley 2003",
      "title": "Hsu, Smith and Young. The Automatic Improvement of Locality in Storage Systems. UCB/CSD-03-1264, July 2003, sections 2-4 and 6.",
      "url": "https://www2.eecs.berkeley.edu/Pubs/TechRpts/2003/Archive/CSD-03-1264.pdf",
      "accessed": "2026-11-13"
    },
    {
      "id": "borg-project",
      "label": "BORG author project",
      "title": "FIU Systems Research Laboratory: BORG project, Code and Traces.",
      "url": "https://sylab-srv.cs.fiu.edu/projects/borg/start",
      "accessed": "2026-11-13"
    }
  ],
  "provenance": [
    "Historical HDD research; source synthesis, not a prototype reproduction or a modern SSD performance prediction."
  ]
}