Messages in this thread | | | Date | Tue, 25 Aug 2009 22:58:49 -0400 | From | Theodore Tso <> | Subject | Re: [patch] ext2/3: document conditions when reliable operation is possible |
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On Tue, Aug 25, 2009 at 09:15:00PM -0400, Ric Wheeler wrote: > > I agree with the whole write up outside of the above - degraded RAID > does meet this requirement unless you have a second (or third, counting > the split write) failure during the rebuild.
The argument is that if the degraded RAID array is running in this state for a long time, and the power fails while the software RAID is in the middle of writing out a stripe, such that the stripe isn't completely written out, we could lose all of the data in that stripe.
In other words, a power failure in the middle of writing out a stripe in a degraded RAID array counts as a second failure.
To me, this isn't a particularly interesting or newsworthy point, since a competent system administrator who cares about his data and/or his hardware will (a) have a UPS, and (b) be running with a hot spare and/or will imediately replace a failed drive in a RAID array.
- Ted
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