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Re: Running on an NFS Mounted Directory

From: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To: Steve Wampler <swampler(at)noao(dot)edu>
Cc: Ketema Harris <ketema(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Running on an NFS Mounted Directory
Date: 2006-04-27 04:55:24
Message-ID: 20060427045524.GV97354@pervasive.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Wed, Apr 26, 2006 at 07:35:42PM -0700, Steve Wampler wrote:
> On Wed, Apr 26, 2006 at 10:06:58PM -0400, Ketema Harris wrote:
> > I was wondering if there were any performance issues with having a data
> > directory that was an nfs mounted drive?  Say like a SAN or NAS device? Has
> > anyone done this before?
>  
> My understanding is that NFS is pretty poor in performance in general,
> so I would expect it to be particularly bad for a DB.  You might run
> some (non-DB) performance tests to get a feel for how bad it might me.
> (Someone once told me that NFS topped out at around 12MB/s, but I don't
> know if that's really true [they were trying to sell a competitive
> networked filesystem]).
> 
> In any event, you're at least limited by ethernet speeds, if not more.

More importantly, the latency involved will kill commit performance. If
it doesn't then it's likely that fsync isn't being obeyed, which means 0
data integrity.
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby(at)pervasive(dot)com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

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