Messages in this thread | | | Date | Tue, 17 Jan 2006 21:10:56 -0500 | From | Phillip Susi <> | Subject | Re: FYI: RAID5 unusably unstable through 2.6.14 |
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Michael Loftis wrote:
> What about I said was inaccurate? I never said that it increases > exponentially or anything like that, just that it does increase, which > you've proven. I was speaking in the case of a RAID-5 set, where the > minimum is 3 drives, so every additional drive increases the chance of > a double fault condition. Now if we're including mirrors and > stripes/etc, then that means we do have to look at the 2 spindle case, > but the third spindle and beyond keeps increasing. If you've a 1% > failure rate, and you have 100+ drives, chances are pretty good you're > going to see a failure. Yes it's a LOT more complicated than that. >
I understood you to be saying that a raid-5 was less reliable than a single disk, which it is not. Maybe I did not read correctly. Yes, a 3 + n disk raid-5 has a higher chance of failure than a 3 disk raid-5, but only slightly so, and in any case, a 3 disk raid-5 is FAR more reliable than a single drive, and only slightly less reliable than a two disk raid-1 ( though you get 3x the space for only 50% higher cost, so 6x cheaper cost per byte of storage ).
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