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zfs-intent-log · shipping · also ZIL

ZFS Intent Log

The ZFS Intent Log is a per-dataset recovery log that can persist filesystem operations before their transaction group reaches stable storage.

Related Observatory article: ZFS Intent Log on hesela.com

Intent records can remain in memory until the TXG commits or be committed to the on-disk ZIL to satisfy a synchronous request; recovery replays relevant persisted records when the dataset is instantiated. The log can live in the main pool without a separate device. [1] [2] Copied records contain data, while an indirect record points to a block written outside the log. Transaction-data byte counters do not measure physical SLOG writes. [3]

Relations

related
zfs-separate-log, zfs-transaction-group, fsync, write-ahead-log, crash-consistency

Citations

  1. OpenZFS 2.3.4: zil.c, log lifecycle, zil_commit and zil_replay (accessed 2026-10-14)
  2. OpenZFS 2.3: zpoolconcepts(7), Intent Log and Cache Devices (accessed 2026-10-14)
  3. OpenZFS 2.3.4: zil.h, indirect and copied log records; statistics units (accessed 2026-10-14)

JSON: /data/terms/zfs-intent-log.json