soft-updates · shipping · also softdep

Soft updates

Soft updates is a filesystem metadata-consistency mechanism that delays unsafe on-disk changes until their update dependencies are satisfied.

Related Observatory article: Soft updates on hesela.com

The original BSD implementation uses per-change tracking and temporary buffer rollback rather than a full metadata journal. [1] FreeBSD also offers soft updates journaling as a separate setting. [3]

Relations

related

metadata-update-dependency, background-fsck, crash-consistency

Limitations

• It does not make every recent application write durable, and unused allocations can require later reclamation. [1]

Citations

1. McKusick and Ganger. Soft Updates: A Technique for Eliminating Most Synchronous Writes in the Fast Filesystem. FREENIX 1999, pp. 1-17, sections 2-4. (accessed 2026-10-15)
2. Hesela: Soft updates and metadata ordering (accessed 2026-10-15)
3. FreeBSD 14.3-RELEASE tunefs(8): distinct soft updates and soft updates journaling settings. (accessed 2026-10-15)

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