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Uberblok

An interactive museum of ZFS, visited room by room: copy-on-write, transaction groups, RAID-Z, the ARC, the ZIL. Every animation is read from the OpenZFS source.

CI passing
An exploded hard drive with copper platters next to a ZFS block tree: a new uberblock at txg 1729 rewrites its path down to one block, while the old tree stays intact.

Storage has always had the same enemies: disks that lie, writes cut short, a crash in the middle of an update. ZFS answers them with a handful of ideas. Uberblok shows them one room at a time, from the code that implements them.

  • Eleven technical rooms: the tree and the uberblock, copy-on-write and self-healing, transaction groups, the vdevs, RAID-Z, snapshots and clones, the ARC, metaslabs and space maps, ZIL and SLOG, send and receive, compression, dedup and encryption.
  • Read in its source: every figure runs a transcription of the code it shows, and every excerpt links to its lines in OpenZFS zfs-2.4.4, frozen at one commit. A script checks that the excerpts are byte-identical to the source.
  • A history wing: from the Sun Microsystems team in 2001 to OpenZFS, every fact linked to its source.
  • Pull the plug: in several rooms you can cut the power mid-write, then import the pool and watch what survives.

The name comes from the uberblock, the root of the ZFS tree and the entry point of a pool: it is the museum’s hall. In French, English and Spanish. Built end to end by the ALGOTITAN agents.