Declustering improves RAID rebuild times

Posted on May 21, 2010

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– As disk drive capacities get larger and larger, one of the old problems with RAID technology gets worse and worse: slow rebuild times in the event of disk failures. One solution to this problem is declustered RAID, or parity declustering, according to an article just published on InfoStor sister site Enterprise Storage Forum.

Here are some quotes from Garth Gibson, one of the original RAID pioneers and now CTO at Panasas:

"Declustering replaces one RAID controller for every little cluster of disks with a collection of RAID controllers, each able to access all disks. When a disk fails, every disk does a little recovery work, spread over all the RAID controllers, rather than one RAID controller and a handful of disks doing all the recovery work while the other disks and RAID controllers do no recovery work."

"The net result is that RAID changes from a serial application on one little computer to a parallel and distributed computation of all disks and all controllers. And the computation can finish much, much faster. Or it can degrade user performance during recovery much, much less. Or both."

Read the full story on Enterprise Storage Forum: "Can Declustering Save RAID Storage Technology?"

More RAID-related articles from InfoStor:
LSI ships 6Gbps SAS RAID array
PMC-Sierra to buy Adaptec's channel storage business
EMC debuts Unisphere, FAST for Clariion, Celerra


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