ZFS Raid Levels

ZFS filesystems automatically stripe across all top-level disk devices. (Mirrors and RAID-Z devices are considered to be top-level devices.) It is not recommended that RAID types be mixed in a pool. (zpool tries to prevent this, but it can be forced with the -fflag.)

The following RAID levels are supported:

  • RAID-0 (striping)
  • RAID-1 (mirror)
  • RAID-Z (similar to RAID 5, but with variable-width stripes to avoid the RAID 5 write hole)
  • RAID-Z2

The zfs man page recommends 3-9 disks for RAID-Z pools.