Received: from localhost (unknown [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id 11BE12E0050 for ; Thu, 20 Mar 2008 18:23:36 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 34531-10 for ; Thu, 20 Mar 2008 18:23:28 -0300 (ADT) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.5 Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.189]) by postgresql.org (Postfix) with ESMTP id AC90B2E004A for ; Thu, 20 Mar 2008 18:23:32 -0300 (ADT) Received: by nf-out-0910.google.com with SMTP id f5so612065nfh.23 for ; Thu, 20 Mar 2008 14:23:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:references; bh=VHgh4t4FwPchBldjTmReSENJFt30jQEryl/ISLG2lb4=; b=jQ57Or96RtyBv5+kg2B5ou6db1S5YybBOoObmyVs/M0BJ4kyfU9qUiQZwtp+zooXd8dcKODE0XsjEJuXqwfivmDUcjTSGYdfun2vu8E984DqQUYRNEcMqgYDL/WDEZeVDMojbhWN2AsIkymDyxviBsrQc45yGJkycwWPcGxarAE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:references; b=SFkxJxHkv3249BGAIFCyZVSddeguX9LeFWW6/CWpIilo+tXzVxKmPoYe8rEe1dqfuGjT0B/INk9bVKEy3pafIvzOKAnZozbyGPf7/hr1iKnA1SqYt/1lTjmltDsRt402SBCAV2+DTj6gdj/QSTCri/1ORI2sCZI+ZNLWLjy1v/o= Received: by 10.150.225.14 with SMTP id x14mr1125357ybg.153.1206048210430; Thu, 20 Mar 2008 14:23:30 -0700 (PDT) Received: by 10.150.225.10 with HTTP; Thu, 20 Mar 2008 14:23:30 -0700 (PDT) Message-ID: Date: Thu, 20 Mar 2008 22:23:30 +0100 From: "Frits Hoogland" To: "Bruce Momjian" Subject: Re: PostgreSQL NetApp and NFS Cc: "Chris Hoover" , "PGSQL Performance" In-Reply-To: <200803202009.m2KK9dc26453@momjian.us> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_978_27246830.1206048210398" References: <1d219a6f0803201232g54924fb3ka206c9b03e4664c7@mail.gmail.com> <200803202009.m2KK9dc26453@momjian.us> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.001 tagged_above=0 required=5 tests=HTML_MESSAGE=0.001 X-Spam-Level: X-Archive-Number: 200803/414 X-Sequence-Number: 29368 ------=_Part_978_27246830.1206048210398 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline 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 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 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@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance > ------=_Part_978_27246830.1206048210398 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline 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. +

--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance

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