From: Dan Stromberg <strombrg@dcs.nac.uci.edu>
Subject: RE: NFS tuning - high performance throughput.
Date: Wed, 15 Jun 2005 12:13:43 -0700
Message-ID: <1118862823.22484.13.camel@seki.nac.uci.edu>
References: <EXCHG2003xdWGHpPnqN000005d1@EXCHG2003.microtech-ks.com>
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Cc: "'M. Todd Smith'" <todd@sohovfx.com>, nfs@lists.sourceforge.net,
	strombrg@dcs.nac.uci.edu
To: Roger Heflin <rheflin@atipa.com>
In-Reply-To: <EXCHG2003xdWGHpPnqN000005d1@EXCHG2003.microtech-ks.com>
Sender: nfs-admin@lists.sourceforge.net
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A bigger dd test should work - if you use about 3x your physical memory,
you'll probably be fine doing it that way.

Another way that may work better in -some- cases, is to umount the
filesystem and re-mount it - except for warm restartable filesystems.

On Wed, 2005-06-15 at 10:28 -0500, Roger Heflin wrote:
> 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.
>=20
>                Roger
> 		   Atipa Technologies.=20
>=20
> > -----Original Message-----
> > From: nfs-admin@lists.sourceforge.net=20
> > [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.
> >=20
> > Roger Heflin wrote:
> >=20
> > >Are you using the same dd test on the local machine test? =20
> > If so cache=20
> > >will be a major factor.
> > >
> > >Also, raid5 stripe size, bigger is almost always better, I would do=20
> > >some testing with different strip sizes and see how it affects the=20
> > >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=20
> > >been mentioned?
> > >
> > >                     Roger
> > > =20
> > >
> > Roger,
> >=20
> > I was told by a consultant we hired to help us with this that=20
> > 5Gb test files should be large enough to blow out the caches.=20
> >  Looking back I realize that must have been when we only had=20
> > 2Gb RAM in the machine ..=20
> > is there a better test I can use to check local rw=20
> > performance, as well is there a formula or recommended way to=20
> > calculate how big a file you should rw to properly check local rw?
> >=20
> > I'll have to ask our soft eng who worked with the consultant=20
> > as to why that particular stripe size was used.  I believe we=20
> > are using md, we attempted to use LVM but ran into some=20
> > problems and had some file inconsistencies that were=20
> > unacceptable so had to back out of it.
> >=20
> > Cheers
> > Todd
> >=20
> > --
> > Systems Administrator
> > ----------------------------------
> > Soho VFX - Visual Effects Studio
> > 99 Atlantic Avenue, Suite 303
> > Toronto, Ontario, M6K 3J8
> > (416) 516-7863
> > http://www.sohovfx.com
> > ----------------------------------
> >=20
> >=20
> > =20
> >=20
> >=20
> >=20
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