Difference between revisions of "RAID-Z"

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RAID-Z integrates redundancy, performance, and data integrity within ZFS's architecture using copy-on-write and checksumming mechanisms.
 
RAID-Z integrates redundancy, performance, and data integrity within ZFS's architecture using copy-on-write and checksumming mechanisms.
  
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=== Features ===
 
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* '''Copy-on-write (COW)''' – All writes are atomic and written to new blocks, preventing corruption from incomplete writes.
 
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* '''Checksumming''' – Every block of data is protected by a checksum, and data is self-healing using redundant copies.
 
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* '''No write hole''' – Unlike traditional RAID, RAID-Z writes data and parity in a single atomic operation, eliminating the risk of mismatched data/parity.
 
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* '''Dynamic striping''' – Automatically balances load across all available disks.
 
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* '''Integrated into ZFS''' – No separate hardware controller or software layer is required.
 
  
 
=== RAID-Z Levels ===
 
=== RAID-Z Levels ===
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=== Example Configuration ===
 
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Create a RAID-Z2 pool with four disks:
 
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<syntaxhighlight lang="bash">
 
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sudo zpool create mypool raidz2 /dev/sd[b-e]
 
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</syntaxhighlight>
 
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Create a filesystem within the pool:
 
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<syntaxhighlight lang="bash">
 
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sudo zfs create mypool/data
 
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</syntaxhighlight>
 
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=== Advantages over Traditional RAID ===
 
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* Atomic writes prevent the RAID write hole
 
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* Native integration with ZFS (no extra tools needed)
 
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* Self-healing from silent data corruption
 
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* More reliable parity management
 
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* Better support for large storage volumes and modern use cases
 
  
 
=== Limitations ===
 
=== Limitations ===
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=== See Also ===
 
=== See Also ===
  
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* [[ZFS]]
 
 
* [[RAID]]
 
* [[RAID]]
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* [[RAID 5]]
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* [[RAID 6]]
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[[Category:Information]]
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* [[Copy-on-write]]
 
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* [[Data integrity]]
 

Latest revision as of 20:44, 12 June 2025

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

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