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From: Emmanuel Florac <eflorac@intellique.com>
To: Markus Stockhausen <stockhausen@collogia.de>
Cc: "xfs@oss.sgi.com" <xfs@oss.sgi.com>
Subject: Re: Writeback Stalls
Date: Thu, 20 Sep 2012 09:12:46 +0200	[thread overview]
Message-ID: <20120920091246.21db5857@galadriel.home> (raw)
In-Reply-To: <12EF8D94C6F8734FB2FF37B9FBEDD1735831B7A3@EXCHANGE.collogia.de>

Le Wed, 19 Sep 2012 18:36:11 +0000 vous écriviez:

> We have an small sized VMWare infrastructure. 8 hosts with round
> about 50 VMs. Their images are hosted on 2 Ubuntu 12.04 NFS storage
> servers with each of them having a 14 disk RAID 6 array. On top of
> the array runs a single XFS filesystem with round about 10TB of disk
> space.

You didn't mention the type of disks and controllers you're using, it
makes a very important difference. Typically in VM environment RAID-6
on 7200RPM drives behaves quite poorly because of very poor random IO
write performance. 
You should also look at the iostat -mx output on the NFS server.
You'll probably see a 100% disk usage with lots of small read and write
IOs.

-- 
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Emmanuel Florac     |   Direction technique
                    |   Intellique
                    |	<eflorac@intellique.com>
                    |   +33 1 78 94 84 02
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      parent reply	other threads:[~2012-09-20  7:11 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-19 18:36 Writeback Stalls Markus Stockhausen
2012-09-19 21:34 ` Dave Chinner
2012-09-20  4:33   ` Markus Stockhausen
2012-09-20  6:05     ` Dave Chinner
2012-09-20  7:12 ` Emmanuel Florac [this message]

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