RAID-Z

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RAID-Z

RAID-Z is a data protection technology used by the ZFS file system. It is a variation of traditional RAID-5/RAID-6 but specifically designed to overcome the limitations and risks associated with conventional RAID, particularly the "write hole" problem.

RAID-Z integrates redundancy, performance, and data integrity within ZFS's architecture using copy-on-write and checksumming mechanisms.


RAID-Z Levels

ZFS supports three levels of RAID-Z:

Level Parity Fault Tolerance Minimum Disks Description
RAID-Z1 Single parity 1 disk failure 3 Similar to RAID-5
RAID-Z2 Double parity 2 disk failures 4 Similar to RAID-6
RAID-Z3 Triple parity 3 disk failures 5 Unique to ZFS; ideal for large arrays


Limitations

  • No native support outside ZFS (tied to ZFS structure)
  • More RAM usage (ZFS recommends at least 8 GB; more for deduplication)
  • RAID-Z arrays cannot be shrunk or have disks removed (though vdevs can be added)

Use Cases

  • Enterprise servers requiring high data integrity
  • Backup and archival storage
  • Virtualization hosts (e.g., Proxmox)
  • NAS systems and home media servers using ZFS

See Also