SUMMARY : raidz zpool question

From: Iain Miller <>
Date: Wed Jul 22 2009 - 06:00:53 EDT
Hi List,

Thanks to

Anthony D'Atri, DRoss-Smith, Chris Hoogendyk, Chris Banal, Hendrik
Visage, Karl Fosburg, Francisco Roque, Eric D. Mudama

Who all basically said not to put all the disks into a single raidz
vdev for varying reasons.  These included

- Increased impact from disk failures. RAIDZ can tolerate two
failures, anymore and the whole data needs restored (from tape)
- Increased time to rebuild array from a single drive failure as the
rebuild will need to access all the drives in the array.
- The number of drives in a RAIDZ set should not exceed 9 drives (any
more than 6 is viewed as "risky")

Other general feedback included
-RAIDZ is really only suited for large IO and if performance is more
important look at mirrors (with the tradeoff of less usable space).
-More RAIDZ pools gives better performance from an IOPS point of view
than one large RAIDZ vdev.
-There's a ZFS best practices guide at

Thanks to you all for the constructive feedback - I am going to go
with the first layout.



Iain Miller
sunmanagers mailing list
Received on Wed Jul 22 06:02:15 2009

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