raidz2
also: RAID-Z2, raidz2 vdev
A RAID level used in ZFS that provides data redundancy with two-disk fault tolerance, allowing the pool to survive simultaneous failure of any two drives without data loss.
raidz2 is a ZFS-specific RAID implementation that distributes data and parity information across multiple disks. It can tolerate the failure of any two drives simultaneously while maintaining data integrity, making it more resilient than RAID 5 (which only tolerates one drive failure).
In a raidz2 pool, data is striped across multiple drives with two independent parity blocks calculated using different algorithms. This redundancy comes at a storage cost: if you have four 1TB drives in raidz2, approximately 2TB is used for parity information, leaving 2TB usable capacity.
Example: zpool create mypool raidz2 sda sdb sdc sdd creates a ZFS pool named 'mypool' across four drives with raidz2 configuration. If sda or sdb fails, the pool continues operating normally. Even if both fail, data can be recovered from the remaining drives using the parity blocks.