From: "Roger Heflin" <rheflin@atipa.com>
Subject: RE: NFS tuning - high performance throughput.
Date: Wed, 15 Jun 2005 10:28:31 -0500
Message-ID: <EXCHG2003xdWGHpPnqN000005d1@EXCHG2003.microtech-ks.com>
References: <42B03F7E.8090206@sohovfx.com>
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To: "'M. Todd Smith'" <todd@sohovfx.com>, <nfs@lists.sourceforge.net>
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Make the dd test bigger, with 2x the memory size, 50% will
be from cache and almost instanteous, with 4x the memory size,
25% will be from cache, bigger runs will get closer to actual
reality, on the tests I do I run things 8x, but if you run
2x, 4x, 8x memory you should get a decent graph to give you
an idea of what the actual value is.

               Roger
		   Atipa Technologies. 

> -----Original Message-----
> From: nfs-admin@lists.sourceforge.net 
> [mailto:nfs-admin@lists.sourceforge.net] On Behalf Of M. Todd Smith
> Sent: Wednesday, June 15, 2005 9:47 AM
> To: nfs@lists.sourceforge.net
> Subject: Re: [NFS] NFS tuning - high performance throughput.
> 
> Roger Heflin wrote:
> 
> >Are you using the same dd test on the local machine test?  
> If so cache 
> >will be a major factor.
> >
> >Also, raid5 stripe size, bigger is almost always better, I would do 
> >some testing with different strip sizes and see how it affects the 
> >speed, I have never seen less than 32k be faster than 32k.
> >
> >Are you using md for the raid5 setup or something else that has not 
> >been mentioned?
> >
> >                     Roger
> >  
> >
> Roger,
> 
> I was told by a consultant we hired to help us with this that 
> 5Gb test files should be large enough to blow out the caches. 
>  Looking back I realize that must have been when we only had 
> 2Gb RAM in the machine .. 
> is there a better test I can use to check local rw 
> performance, as well is there a formula or recommended way to 
> calculate how big a file you should rw to properly check local rw?
> 
> I'll have to ask our soft eng who worked with the consultant 
> as to why that particular stripe size was used.  I believe we 
> are using md, we attempted to use LVM but ran into some 
> problems and had some file inconsistencies that were 
> unacceptable so had to back out of it.
> 
> Cheers
> Todd
> 
> --
> Systems Administrator
> ----------------------------------
> Soho VFX - Visual Effects Studio
> 99 Atlantic Avenue, Suite 303
> Toronto, Ontario, M6K 3J8
> (416) 516-7863
> http://www.sohovfx.com
> ----------------------------------
> 
> 
>  
> 
> 
> 
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