Basic Concepts

How OpenZFS is put together and what its features actually do.

If you are new to ZFS, read Copy-on-Write first — most of what follows is a consequence of it — and then VDEVs, since pool layout is the decision that is hardest to change later.

These pages explain concepts and trade-offs; the man pages remain the reference for exact syntax and options.

• Copy-on-Write
  • The tree
  • Writing something
  • Transaction groups
  • What follows from it
  • The costs
  • Further reading
• Pool Structure
  • VDEVs
  • RAIDZ
  • dRAID
  • Caching and Auxiliary Devices
  • Special vdev
  • Changing Pool Layout
  • Feature Flags
• Datasets
  • Datasets and Properties
  • ZVOLs
  • Snapshots, Clones and Bookmarks
  • Quotas and Reservations
  • ACLs and Extended Attributes
• Data Storage
  • Checksums and Their Use in ZFS
  • Compression
  • Deduplication
  • Block Cloning
  • Native Encryption
• Operations
  • Send and Receive
  • Scrub and Resilver
  • TRIM
  • Sharing Datasets
  • Delegated Administration
  • Pools at Boot
  • Troubleshooting