Message-ID: <4D2285CF.3050304@2ndquadrant.com>
Date: Mon, 03 Jan 2011 21:28:31 -0500
From: Greg Smith <greg@2ndquadrant.com>
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To: Mladen Gogala <mladen.gogala@vmsinfo.com>
CC: Rich <rhdyes@gmail.com>,
	"pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Performance of PostgreSQL over NFS
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Mladen Gogala wrote:
> Rich wrote:
>> I am wondering why anyone would do that?  Too much overhead and no 
>> reliable enough.
>
> Apparently, NetApp  thinks that  it is reliable. They're selling that 
> stuff  for years.  I know that Oracle works with NetApp, they even 
> have their own user mode NFS client driver, I am not sure about 
> PostgreSQL. Did anybody try that?
>

You have hit upon the crucial distinction here.  In order for NFS to 
work well, you need a rock solid NFS server.  NetApp does a good job 
there.  You also need a rock solid NFS client, configured perfectly in 
order to eliminate the risk of corruption you get if the NFS 
implementation makes any mistake in handling sync operations or error 
handling.  The issue really isn't "will PostgreSQL performance well over 
NFS?".  The real concern is "will my data get corrupted if my NFS client 
misbehaves, and how likely is that to happen?"  That problem is scary 
enough that whether or not the performance is good is secondary.  And 
unlike Oracle, there hasn't been much full end to end integration to 
certify the reliability of PostgreSQL in this context, the way 
NetApp+Oracle has worked out those issues.  It's hard to most of us to 
even justify that investigation, given that NFS and NetApp's offerings 
that use it feel like legacy technologies, ones that are less relevant 
every year.

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services and Support        www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books