{
  "slug": "journal-checkpoint",
  "term": "Journal checkpoint",
  "aliases": [
    "JBD2 checkpoint"
  ],
  "definition": "A journal checkpoint writes committed journaled state to its home locations so the corresponding log space can be reclaimed.",
  "note": "This is not the same event as committing recovery information to the journal. In JBD2, checkpointing concerns committed buffers and journal-space management. [api] Do not infer an application's transaction boundary from this filesystem mechanism. [hesela]",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "The cited Linux v6.12 mechanism and explanatory model do not certify a deployed kernel or storage stack.",
      "citationIds": [
        "hesela"
      ]
    }
  ],
  "related": [
    "crash-consistency",
    "write-ahead-log",
    "database-checkpoint",
    "journal-revoke-record",
    "ext4-fast-commit"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "api",
      "title": "Linux v6.12: The Linux Journalling API, checkpointing",
      "url": "https://www.kernel.org/doc/html/v6.12/filesystems/journalling.html",
      "accessed": "2026-10-14"
    },
    {
      "id": "hesela",
      "title": "Hesela: Ext4 journal replay, revocation and repeatable recovery",
      "url": "https://hesela.com/analyses/ext4-journal-replay-revocation/",
      "accessed": "2026-10-14"
    }
  ],
  "updated": "2026-10-14"
}