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hello. My understanding is that Greg has done some of this work
already. He helped me solve a problem which was causing large disks to
fail to reconstruct after a disk failure. The failure was due to an
over-use of kernel memory to keep track of all the parity regions. So,
while I don't know much about this topic, I'm hopeful that we're somewhat
along the path to this happy day. Reducing the time it takes to clean
parity on a raid set would be a beautiful thing.
On Aug 1, 12:17am, Thor Lancelot Simon wrote:
} Subject: Re: WAPBL
} On Thu, Jul 31, 2008 at 09:48:00PM +0100, Matthias Scheler wrote:
} > Any brilliant ideas how to teach RAIDframe (ETA for parity rewrite
} > is 1:28 hours) to perform only limited parity rewrites after a crash?
} I think the parity logging code could be enhanced to do this (in addition
} to providing the significant performance benefit it should already provide).
} It divides the volume into "parity regions" already, so it should be possible
} to add a clean bit per parity region, set after each parity log transaction
} Greg says the parity log code has some problems with large disks -- it
} doesn't use large enough regions (they seem to be fixed size), so it
} wants e.g. 1GB of kernel memory per 1TB of managed disk. But that could
} presumably be addressed.
} I am *not* volunteering to do this.
} Thor Lancelot Simon
} "My guess is that the minimal training typically provided would only
} have given the party in question multiple new and elaborate ways to do
} something incomprehensibly stupid and dangerous." -Rich Goldstone
>-- End of excerpt from Thor Lancelot Simon
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