From: Christoph Hellwig <hch@infradead.org>
To: Michael Monnerie <michael.monnerie@is.it-management.at>
Cc: xfs@oss.sgi.com
Subject: Re: disk performance strange/low
Date: Mon, 17 Aug 2009 17:41:36 -0400 [thread overview]
Message-ID: <20090817214136.GA26060@infradead.org> (raw)
In-Reply-To: <200908172311.07660@zmi.at>
On Mon, Aug 17, 2009 at 11:11:07PM +0200, Michael Monnerie wrote:
> I've got an Areca RAID Controller with 5x 1TB disks, and in the last
> time I often found it to be strange. Now I investigated, and found this.
> >From another server I NFS mount a share, and make
> dd if=/dev/sda of=/server/share/test.dd bs=1024k
> so that should do big sequential writes. But the performance goes up and
> down, like you see in this output from "iostat -kx 5 555". You see write
> KB/s is 5824, 23207, 87283, 704, 40187. Up and down all the time. Could
> that be solved by the patch you discussed last time, or is there
> something else?
Yes, that sounds like the problem of the VM not feeding us enough
pages to write. What kernel is this on? Latest 2.6.31-rc has a
workaround for it.
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next prev parent reply other threads:[~2009-08-17 21:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-17 21:11 disk performance strange/low Michael Monnerie
2009-08-17 21:41 ` Christoph Hellwig [this message]
2009-08-18 2:08 ` Michael Monnerie
2009-08-18 2:43 ` Christoph Hellwig
2009-08-26 17:20 ` Michael Monnerie
2009-08-26 17:56 ` Christoph Hellwig
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