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Re: PostgreSQL NetApp and NFS

From: "Frits Hoogland" <frits(dot)hoogland(at)gmail(dot)com>
To: "Bruce Momjian" <bruce(at)momjian(dot)us>
Cc: "Chris Hoover" <revoohc(at)gmail(dot)com>, "PGSQL Performance" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: PostgreSQL NetApp and NFS
Date: 2008-03-20 21:23:30
Message-ID: fbb8fbcd0803201423h27df25d5v5801f77f2a0e4031@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
My experience postgresql work good on NFS. Of course, use NFS over TCP, and
use noac if you want to protect your database even more (my experience is
NFS client caching doesn't lead to an irrecoverable database however)

I've encountered problems with RHEL4 as a database server and a client of a
Netapp filer, due to a bug in the (redhat nfs client)
Postgresql uses BSD read/write semantics. The BSD semantics mean an IO call
(either read or write) is atomic.
Linux uses system V read/write semantics. The system V semantics mean an IO
is NOT atomic and can be interrupted.
A read call got interrupted (due to the bug in the nfs client), which meant
the IO call kept waiting until infinity.
It even caused all other IO done against the inode to be waiting, leading to
a situation where the server needed a reboot to be able to function
propertly.

frits

On Thu, Mar 20, 2008 at 9:09 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:

> Chris Hoover wrote:
> > If you have any real life good or bad stories, I'd love to hear it.
>  Given
> > the NetApp arrays supposedly being very good NFS platforms, overall, is
> this
> > a recommended way to run PostgreSQL, or is it recommended to not run
> this
> > way.
>
> We do have an NFS section in our documentation at the bottom of this
> page:
>
>        http://www.postgresql.org/docs/8.3/static/creating-cluster.html
>
> --
>  Bruce Momjian  <bruce(at)momjian(dot)us>        http://momjian.us
>  EnterpriseDB                             http://postgres.enterprisedb.com
>
>  + If your life is a hard drive, Christ can be your backup. +
>
> --
> Sent via pgsql-performance mailing list (pgsql-performance(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance
>

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Subject: Re: PostgreSQL NetApp and NFS
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