Date: Tue, 18 Apr 2006 06:40:25 -0500 From: Eric Anderson <anderson@centtech.com> To: David Gilbert <dgilbert@dclg.ca> Cc: FreeBSD ISP <freebsd-isp@freebsd.org>, Francisco Reyes <lists@stringsutils.com> Subject: Re: NFS optimization Message-ID: <4444D029.8060109@centtech.com> In-Reply-To: <17475.54375.95109.55657@canoe.dclg.ca> References: <cone.1144794037.918896.59848.1000@zoraida.natserv.net> <17475.43946.264571.52593@canoe.dclg.ca> <cone.1145294815.465429.96480.1000@zoraida.natserv.net> <17475.54375.95109.55657@canoe.dclg.ca>
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David Gilbert wrote: >>>>>> "Francisco" == Francisco Reyes <lists@stringsutils.com> writes: > > Francisco> What would be a good way to determine how many nfsd > Francisco> proccesses one should have? I erred in the side of caution > Francisco> since had to literally through an NFS setup into production > Francisco> without been able to do much testing. Set 35 processes. My > Francisco> busiest nfsd are: 250 hours 50 " 24 " 11 " 7 " 4 " 3 " 2 " > Francisco> 1 " > > Francisco> The rest are under 1 hour. Does that mean that I should be > Francisco> ok with 10 processes? > > Roughly, yes. You'll see NFSd's normally decline exponentially with > an inflection point. If your machine is completely dedicated to NFS, > you probably want to run lots. The overhead of extra NFSd processes > is fairly small. If you rarely do NFS, the default of 4 may even be > overkill. > > Consider that if you are "out" of nfsd's, the penalty is increased > latency for some small number of transactions that wait for an nfsd to > become available.. Even if you have tonnes of NFSd processes, if disk > is a limiting factor, more nfsd's won't speed the process. I have found that having too little can easily cause clients to block on nfs under peak usage times, so I tend to bump the number way up. There's little to no harm in it. > Something that most peoople don't consider is that the number of NFSd > process can balance the concurrency of NFS clients against local disk > requirements. If, say, you run a busy database on the NFS server, you > may want run fewer NFSd process to increase the disk bandwidth > resources available to the database. > > Francisco> To kill the least active ones, I just "kill" them? or is > Francisco> there a better way to restart the whole nfs server side? > > I rarely 'kill' an nfsd. Always thought that was bad. Killing any > nfsd is equivalent. If you kill one that is further up the queue, the > ones later in the queue move up (AFAIK). Still... I always change the > boot parameters and leave the processes currently running when I tune > the number of nfsd's. I usually look at my nfsd's, and see what the distribution of run time is on them. I like to see at minimum a few (maybe 5% or so) with 0:00.00 runtime - which (to me) means that I had enough to service the queue, and a few extra that were bored. For my setup, this means typically between 256 and 512 nfsd's (with one server at 1024). Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------
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