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From: Michael Monnerie <michael.monnerie@is.it-management.at>
To: xfs@oss.sgi.com
Cc: Richard Scobie <richard@sauce.co.nz>
Subject: Re: XFS over LVM over md RAID
Date: Fri, 10 Sep 2010 02:25:55 +0200	[thread overview]
Message-ID: <201009100225.55562@zmi.at> (raw)
In-Reply-To: <4C89668E.6010800@sauce.co.nz>


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On Freitag, 10. September 2010 Richard Scobie wrote:
> Limited testing using dd and bonnie++ shows no difference in write 
> performance
 
For dd it should always show the same, as you just sequentially write a 
large file. Only with bonnie you would see differences due to stripe 
sets, as the speed only drops when doing I/O not on boundaries and/or 
smaller than the stripe size, as the stripe size is the smallest 
possible I/O for the RAID.

I don't know why you don't see any difference with bonnie though.

FWIW, a stripe set of 256k means you do read/write 256k from a single 
drive on each I/O, then the next 256k from the next drive. I hope you 
have very few small accesses and mostly very large files. If you'd use a 
database on that system it would crawl...

-- 
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Michael Monnerie, Ing. BSc

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  reply	other threads:[~2010-09-10  0:25 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-09 22:58 XFS over LVM over md RAID Richard Scobie
2010-09-10  0:25 ` Michael Monnerie [this message]
2010-09-10  0:52   ` Richard Scobie
2010-09-10  1:14   ` Richard Scobie
2010-09-10  1:30 ` Dave Chinner
2010-09-10  2:29   ` Richard Scobie
2010-09-10 14:24     ` Eric Sandeen
2010-09-10 21:42       ` Richard Scobie
2010-09-10 22:19         ` Stan Hoeppner
  -- strict thread matches above, loose matches on Subject: below --
2010-09-10 23:08 Richard Scobie

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