Re: PostgreSQL NetApp and NFS - Mailing list pgsql-performance

From Frits Hoogland
Subject Re: PostgreSQL NetApp and NFS
Date
Msg-id fbb8fbcd0803201423h27df25d5v5801f77f2a0e4031@mail.gmail.com
Whole thread Raw
In response to Re: PostgreSQL NetApp and NFS  (Bruce Momjian <bruce@momjian.us>)
List 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@momjian.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@momjian.us>        http://momjian.us
 EnterpriseDB                             http://postgres.enterprisedb.com

 + If your life is a hard drive, Christ can be your backup. +

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