{
  "status": "research",
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": {
    "date": "2011",
    "citationIds": [
      "tang-fvd"
    ]
  },
  "lastSeen": null,
  "updated": "2026-10-21",
  "advantages": [],
  "limitations": [
    "The 2011 prototype evaluation is not evidence of present-day QCOW2 performance."
  ],
  "slug": "fast-virtual-disk",
  "term": "Fast Virtual Disk (FVD)",
  "aliases": [
    "FVD"
  ],
  "definition": "Fast Virtual Disk is a research virtual-disk format that separates copy-on-write tracking from storage allocation.",
  "note": "Architecture: Tang's FVD uses a bitmap for data location and an optional lookup table for allocation. Copy-on-read caches base-image data locally; adaptive prefetching can fetch remaining blocks. [tang-fvd]\n\nScope: the published comparison disabled copy-on-read and prefetching. It does not evaluate today's QCOW2 external-data feature. [tang-fvd]",
  "related": [
    "qcow2",
    "copy-on-write",
    "thin-provisioning"
  ],
  "citations": [
    {
      "id": "tang-fvd",
      "title": "Chunqiang Tang (2011), FVD: a High-Performance Virtual Machine Image Format for Cloud, USENIX ATC 11, sections 2-4",
      "url": "https://www.usenix.org/legacy/event/atc11/tech/final_files/Tang.pdf",
      "accessed": "2026-10-21"
    }
  ],
  "provenance": [
    "Historical research design, not a claim of current product availability or a Hesela benchmark."
  ]
}