{
  "slug": "minimum-io-size",
  "term": "Minimum I/O size",
  "aliases": [
    "minimum_io_size",
    "MIN-IO",
    "io_min"
  ],
  "definition": "Minimum I/O size is a Linux block-layer hint for the preferred smallest request granularity, not the smallest addressable unit.",
  "note": "The value is in bytes. Linux raises io_min to at least physical_block_size during queue-limit validation, so equality can reflect a default rather than a measured optimum. [linux-limits]",
  "advantages": [
    {
      "text": "The read-only blockdev --getiomin query exposes the value for a selected block-device path.",
      "citationIds": [
        "blockdev"
      ]
    }
  ],
  "limitations": [
    {
      "text": "A performance hint does not replace logical-sector or direct-I/O validity checks.",
      "citationIds": [
        "linux-abi"
      ]
    }
  ],
  "related": [
    "optimal-io-size",
    "alignment-offset",
    "logical-sector",
    "physical-sector",
    "partition-alignment",
    "direct-io-alignment"
  ],
  "provenance": [
    "Linux semantics pinned to v6.12; query documentation pinned to util-linux v2.40.2. No performance measurement is implied."
  ],
  "citations": [
    {
      "id": "linux-abi",
      "title": "Linux 6.12: stable sysfs block ABI, sector sizes and I/O topology",
      "url": "https://raw.githubusercontent.com/torvalds/linux/v6.12/Documentation/ABI/stable/sysfs-block",
      "accessed": "2026-10-19"
    },
    {
      "id": "linux-limits",
      "title": "Linux 6.12: block limits validation and bdev_alignment_offset",
      "url": "https://raw.githubusercontent.com/torvalds/linux/v6.12/block/blk-settings.c",
      "accessed": "2026-10-19"
    },
    {
      "id": "blockdev",
      "title": "util-linux 2.40.2: blockdev query options and byte units",
      "url": "https://raw.githubusercontent.com/util-linux/util-linux/v2.40.2/disk-utils/blockdev.8.adoc",
      "accessed": "2026-10-19"
    },
    {
      "id": "hesela-sector-alignment",
      "title": "Hesela: 512e, 4Kn and alignment: geometry is not durability",
      "url": "https://hesela.com/analyses/sector-sizes-alignment-not-durability/",
      "accessed": "2026-10-19"
    }
  ],
  "status": "shipping",
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-19"
}