[CentOS-virt] Slightly OT: FakeRaid or Software Raid

Christopher G. Stach II cgs at ldsys.net
Thu Dec 3 21:50:55 UTC 2009

----- "Grant McWilliams" <grantmasterflash at gmail.com> wrote:

> RAID 5 is faster than RAID 10 for reads and writes.

*Serial* reads and writes. That is not the access pattern that you will have in most virtualization hosts.

> What wasn't in the test (but is in others that they've done) is RAID
> 6. I'm not sure I'm sold on it because it gives us about the same
> level of redundancy as RAID 10 but with less performance than RAID 5.
> Theoretically it would get soundly trounced by RAID 10 on IOs and
> maybe be slower on r/w transfer as well.

RAID 6 is pretty slow, but you can stripe them as RAID 60. If you need that kind of fault tolerance, the performance hit is negligible. On high volume boxes with low performance requirements, say NLS on an 8-12 bay 2U or 3U machine, I use RAID 6 with one hot spare.

Christopher G. Stach II

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