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From: Neil Brown <neilb@suse.de>
To: Justin Piszcz <jpiszcz@lucidpixels.com>
Date: Thu, 29 Mar 2007 16:25:04 +1000
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Cc: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org
Subject: Re: Software RAID (non-preempt) server blocking question. (2.6.20.4)
In-Reply-To: message from Justin Piszcz on Tuesday March 27
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On Tuesday March 27, jpiszcz@lucidpixels.com wrote:
> I ran a check on my SW RAID devices this morning.  However, when I did so, 
> I had a few lftp sessions open pulling files.  After I executed the check, 
> the lftp processes entered 'D' state and I could do 'nothing' in the 
> process until the check finished.  Is this normal?  Should a check block 
> all I/O to the device and put the processes writing to a particular device 
> in 'D' state until it is finished?

No, that shouldn't happen.  The 'check' should notice any other disk
activity and slow down if anything else is happening on the device.

Did the check run to completion?  And if so, did the 'lftp' start
working normally again?

Did you look at "cat /proc/mdstat" ?? What sort of speed was the check
running at?

NeilBrown