====== RAIDZ ======


  * RAIDZ-1 A variation on RAID-5, single parity. Requires at least 3 disks.
  * RAIDZ-2 A variation on RAID-5, double parity. Requires at least 4 disks.
  * RAIDZ-3 A variation on RAID-5, triple parity. Requires at least 5 disks. 

[[https://openzfs.github.io/openzfs-docs/Basic%20Concepts/RAIDZ.html#space-efficiency|Space efficiency]]
===== Adding more HDDs =====

Not possible now.
It is possible to extend space by adding similar vdev (raidz based)

[[https://github.com/openzfs/zfs/discussions/12467|Expanding usable capacity on raidz pools by adding devices #12467]]
[[https://github.com/openzfs/zfs/pull/12225|RAIDZ Expansion feature #12225]]

Check features:
<code bash>zpool get all backuppool</code>