From: NeilBrown <neilb@suse.de>
To: thomas@fjellstrom.ca
Cc: linux-raid@vger.kernel.org
Subject: Re: potentially lost largeish raid5 array..
Date: Sun, 25 Sep 2011 19:37:47 +1000 [thread overview]
Message-ID: <20110925193747.074d965b@notabene.brown> (raw)
In-Reply-To: <201109231026.53770.thomas@fjellstrom.ca>
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On Fri, 23 Sep 2011 10:26:53 -0600 Thomas Fjellstrom <thomas@fjellstrom.ca>
wrote:
> On September 23, 2011, NeilBrown wrote:
> > On Fri, 23 Sep 2011 02:09:36 -0600 Thomas Fjellstrom <thomas@fjellstrom.ca>
> >
> > wrote:
> > > I forgot to say, but: Thank you very much :) for the help, and your
> > > tireless work on md.
> >
> > You've very welcome .... but I felt I needed to respond to that word
> > "tireless".
> > The truth is that I am getting rather tired of md .... if anyone knows
> > anyone who wants to get into kernel development and is wondering where to
> > start - please consider whispering 'the md driver' in their ear. Plenty
> > to do, great mentoring possibilities, and competent linux kernel engineers
> > with good experience are unlikely to have much trouble finding a job ;-)
> >
> > NeilBrown
>
> Very tempting. How much work do you think it would be to add in full raid10
> reshape support? ;D (not that I'm volunteering, I don't think I could
> comprehend a lot of the raid code, at least not at this point in time
> (extenuating circumstances)).
>
RAID10 reshape is more complicated than RAID5/6 reshape because there are
more options - more combinations.
So you would probably implement a subset of possible reshapes. And then
maybe implement another subset.
Providing you have:
- a clear understanding of the intermediate state and a way to record
that state in the metadata
- a way to tell if a given block is in the 'old' layout or the 'new' layout
or 'being reshaped'
- somewhere in memory to store all the blocks that are 'being reshaped'
it should be fairly easy. RAID5/6 has a stripe-cache so the last point is
trivial. Handling that in RAID10 is probably the biggest single part of the
task.
So: not a trivial task, but not an enormous task either.... which doesn't
narrow it down very much I guess.
NeilBrown
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next prev parent reply other threads:[~2011-09-25 9:37 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-23 1:50 potentially lost largeish raid5 array Thomas Fjellstrom
2011-09-23 4:32 ` NeilBrown
2011-09-23 4:49 ` Thomas Fjellstrom
2011-09-23 4:58 ` Roman Mamedov
2011-09-23 5:10 ` Thomas Fjellstrom
2011-09-23 7:06 ` David Brown
2011-09-23 7:37 ` Thomas Fjellstrom
2011-09-23 12:56 ` Stan Hoeppner
2011-09-23 13:28 ` David Brown
2011-09-23 16:22 ` Thomas Fjellstrom
2011-09-23 23:24 ` Stan Hoeppner
2011-09-24 0:11 ` Thomas Fjellstrom
2011-09-24 12:17 ` Stan Hoeppner
2011-09-24 13:11 ` (unknown) Tomáš Dulík
2011-09-24 15:16 ` potentially lost largeish raid5 array David Brown
2011-09-24 16:38 ` Stan Hoeppner
2011-09-25 13:03 ` David Brown
2011-09-25 14:39 ` Stan Hoeppner
2011-09-25 15:18 ` David Brown
2011-09-25 23:58 ` Stan Hoeppner
2011-09-26 10:51 ` David Brown
2011-09-26 19:52 ` Stan Hoeppner
2011-09-26 20:29 ` David Brown
2011-09-26 23:28 ` Krzysztof Adamski
2011-09-27 3:53 ` Stan Hoeppner
2011-09-24 17:48 ` Thomas Fjellstrom
2011-09-24 5:59 ` Mikael Abrahamsson
2011-09-24 17:53 ` Thomas Fjellstrom
2011-09-25 18:07 ` Robert L Mathews
2011-09-26 6:08 ` Mikael Abrahamsson
2011-09-26 2:26 ` Krzysztof Adamski
2011-09-23 5:11 ` NeilBrown
2011-09-23 5:22 ` Thomas Fjellstrom
2011-09-23 8:09 ` Thomas Fjellstrom
2011-09-23 9:15 ` NeilBrown
2011-09-23 16:26 ` Thomas Fjellstrom
2011-09-25 9:37 ` NeilBrown [this message]
2011-09-24 21:57 ` Aapo Laine
2011-09-25 9:18 ` Kristleifur Daðason
2011-09-25 10:10 ` NeilBrown
2011-10-01 23:21 ` Aapo Laine
2011-10-02 17:00 ` Aapo Laine
2011-10-05 2:13 ` NeilBrown
2011-10-05 2:06 ` NeilBrown
2011-11-05 12:17 ` Alexander Lyakas
2011-11-06 21:58 ` NeilBrown
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