{
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-20",
  "slug": "fat-cluster-chain",
  "term": "FAT cluster chain",
  "aliases": [
    "File Allocation Table cluster chain"
  ],
  "definition": "A FAT cluster chain represents an allocation as an ordered sequence of cluster links ending in an end-of-chain marker.",
  "note": "In Linux v6.12's exFAT code, chain traversal follows each FAT entry to the next cluster. A separate helper can create links between consecutive clusters, so the existence of a chain does not establish fragmentation. [linux-fat]\n\nA synthetic ordering example: 20, 21, 22 and 20, 22, 21 occupy the same cluster set but order the file differently. Counting consecutive forward runs yields one and three, respectively. These are volume-cluster runs, not physical NAND locations or device-request counts.",
  "related": [
    "exfat",
    "allocation-bitmap",
    "filesystem-aging",
    "free-space-fragmentation"
  ],
  "citations": [
    {
      "id": "linux-fat",
      "title": "Linux v6.12: exFAT chain traversal and allocation, fs/exfat/fatent.c",
      "url": "https://github.com/torvalds/linux/blob/v6.12/fs/exfat/fatent.c",
      "accessed": "2026-10-20"
    }
  ],
  "provenance": [
    "The numeric sequences illustrate ordering only; they are not a complete volume image, measured workload or Linux allocator trace."
  ]
}