From: Neil Brown <neilb@suse.de>
To: "Miro Dietiker, MD Systems" <info@md-systems.ch>
Date: Sun, 13 Nov 2005 21:41:12 +1100
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Message-ID: <17271.6216.944507.182685@cse.unsw.edu.au>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: Locking md device and system for several seconds
In-Reply-To: message from Miro Dietiker, MD Systems on Sunday November 13
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On Sunday November 13, info@md-systems.ch wrote:
> Hi!
> 
> I'm using kernel 2.6.14.2 with md (RAID1 static) as bootable.
> 
> While md synching (initial creation or after marked one as failed,
> removed and re-added) there are some locking problems with the
> complete system/kernel.

Can you check which IO scheduler the drives are using, try different
schedulers, and see if it makes a different.

     grep . /sys/block/*/queue/scheduler

will show you (the one in [brackets] is active). 
Then just echo a new value out to each file.

I've had one report that [anticipatory] causes this problem and [cfq]
removes it.  Could you confirm that?

Thanks,

NeilBrown

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