ZFS Pool Version 2
This page describes the features available with version 2 of the ZFS pool on-disk format. This version includes support for "Ditto Blocks", or replicated metadata. Due to the tree-like structure of the ZFS on-disk format, an uncorrectable error in a leaf block may be relatively benign, while an uncorrectable error in pool metadata can result in an unopenable pool. This feature introduces automatic replication of metadata (up to 3 copies of each block) independent of any underlying pool-wide redundancy. For example, on a pool with a single mirror, the most critical metadata will appear three times on each side of the mirror, for a total of six copies. This ensures that while user data may be lost due to corruption, all data in the pool will be discoverable and the pool will still be usable. This will be expanded in the future to allow user data replication on a per-dataset basis.
This feature was integrated on 4/10/06 with the following bug fix:
6410698 ZFS metadata needs to be more highly replicated (ditto blocks)
This feature is available in:
- Solaris Express Community Edition, build 38
- Solaris 10 10/06 release (build 09)