Re: [patch] ext2/3: document conditions when reliable operation ispossible

From: Rik van Riel
Date: Wed Aug 26 2009 - 23:31:05 EST


Pavel Machek wrote:
Hi!

Ok, can you help? Having a piece of MD documentation explaining the
"powerfail nukes entire stripe" and how current filesystems do not
deal with that would be nice, along with description when exactly that
happens.
Except of course for the inconvenient detail that a power
failure on a degraded RAID 5 array does *NOT* nuke the
entire stripe.

Ok, you are right. It will nuke unrelated sector somewhere on the
stripe (one that is "old" and was not recently written) -- which is
still something ext3 can not reliably handle.

Not quite unrelated. The "nuked" sector will be the one
that used to live on the disk that is broken and no longer
a part of the RAID 5 array.

I wouldn't qualify a missing hard disk as a software issue...

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