{
  "slug": "range-write",
  "term": "Range write",
  "aliases": [
    "Range writes"
  ],
  "definition": "A range write lets a storage device select a contiguous destination within client-approved address ranges and return the chosen starting address.",
  "note": "The OSDI 2008 research interface includes alignment and keeps blocks within one multi-block write in order. The filesystem supplies permissible free space and records the returned address; it does not surrender allocation policy. [range2008]\n\nOverlapping outstanding ranges require temporary device-side tracking of occupied targets. Completion alone cannot retire that tracking: another request may still contain an outdated range. The proposal adds a barrier asserting that later requests account for earlier allocation decisions; pre-barrier writes must also complete before the device forgets them. [range2008]\n\nThe evaluation separates DiskSim/ext2 simulation from Bark, a software layer that skips journal positions on HDDs. Bark's recovery reconstruction was not fully implemented. Those performance experiments do not establish crash-safe deployment. [range2008]",
  "status": "research",
  "advantages": [],
  "limitations": [
    {
      "text": "Flexible write placement can harm later sequential reads; the filesystem must constrain layout accordingly.",
      "citationIds": [
        "range2008"
      ]
    }
  ],
  "related": [
    "free-space-fragmentation",
    "logical-block-address",
    "nameless-write",
    "freeblock-scheduling"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-09",
  "citations": [
    {
      "id": "range2008",
      "title": "Anand et al. Avoiding File System Micromanagement with Range Writes. OSDI 2008, pp. 161-176, sections 3, 5 and 6.",
      "url": "https://static.usenix.org/events/osdi08/tech/full_papers/anand/anand_html/index.html",
      "accessed": "2026-11-09"
    },
    {
      "id": "hesela",
      "title": "Hesela: Range writes preserve choice, not allocation independence",
      "url": "https://hesela.com/analyses/filesystem-aging-free-space-fragmentation/#range-writes",
      "accessed": "2026-11-09"
    }
  ],
  "provenance": [
    "Historical research interface, not a claimed current NVMe feature or reproduced hardware benchmark."
  ]
}