{
  "slug": "thin-pool-metadata",
  "term": "Thin-pool metadata",
  "aliases": [
    "LVM thin-pool metadata"
  ],
  "definition": "The dm-thin mapping and allocation information stored in a separate logical metadata device to track how thin volumes use a pool's data blocks.",
  "note": "The active LVM component has a _tmeta suffix. It is distinct from volume-group configuration metadata. A _pmspare is used as repair output, not active free metadata capacity or a current backup. [lvmthin] Linux v6.12 distinguishes metadata-space mode from failed metadata operations; inspect needs_check and logs, not just Meta% or ro. [dm-thin-source]\n\nvgcfgbackup omits these mappings. A reserve_metadata_snap inspection view is not a thin-volume data snapshot, and exporting mappings does not copy payload blocks. thin_dump 0.9.0 requires metadata-snapshot mode when reading live metadata. [lvmthin] [dm-thin-doc] [thin-dump]",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "A repaired mapping structure does not by itself verify filesystem or application consistency.",
      "citationIds": [
        "lvmthin"
      ]
    }
  ],
  "related": [
    "thin-pool",
    "thin-provisioning",
    "lvm",
    "snapshot"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "lvmthin",
      "title": "LVM2 lvmthin(7): pool components, usage counters and metadata repair",
      "url": "https://man7.org/linux/man-pages/man7/lvmthin.7.html",
      "accessed": "2026-10-17"
    },
    {
      "id": "dm-thin-source",
      "title": "Linux v6.12: dm-thin.c, pool modes, timeout, failed metadata operations and resize",
      "url": "https://github.com/torvalds/linux/blob/v6.12/drivers/md/dm-thin.c",
      "accessed": "2026-10-17"
    },
    {
      "id": "hesela-allocation",
      "title": "Hesela: Sparse files, preallocation and thin-pool capacity",
      "url": "https://hesela.com/analyses/sparse-files-preallocation-thin-capacity/",
      "accessed": "2026-10-17"
    },
    {
      "id": "dm-thin-doc",
      "title": "Linux v6.12 dm-thin: create_snap and reserve_metadata_snap are different operations",
      "url": "https://raw.githubusercontent.com/torvalds/linux/v6.12/Documentation/admin-guide/device-mapper/thin-provisioning.rst",
      "accessed": "2026-10-17"
    },
    {
      "id": "thin-dump",
      "title": "thin-provisioning-tools 0.9.0: thin_dump(8), live-metadata restrictions and output formats",
      "url": "https://manpages.debian.org/bookworm/thin-provisioning-tools/thin_dump.8.en.html",
      "accessed": "2026-10-17"
    }
  ],
  "updated": "2026-10-17"
}