Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id 73F991337B5A for ; Wed, 1 Dec 2010 12:35:43 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 59774-07 for ; Wed, 1 Dec 2010 16:35:35 +0000 (UTC) X-Greylist: delayed 00:21:34.636031 by SQLgrey-1.7.6 Received: from mail-pw0-f46.google.com (mail-pw0-f46.google.com [209.85.160.46]) by mail.postgresql.org (Postfix) with ESMTP id 303A9133740B for ; Wed, 1 Dec 2010 12:35:35 -0400 (AST) Received: by pwj3 with SMTP id 3so1144658pwj.19 for ; Wed, 01 Dec 2010 08:35:34 -0800 (PST) Received: by 10.143.16.6 with SMTP id t6mr9056359wfi.113.1291219544142; Wed, 01 Dec 2010 08:05:44 -0800 (PST) Received: from [192.168.1.102] (shield1.sb.becknet.com [206.83.1.2]) by mx.google.com with ESMTPS id f5sm150608wfg.14.2010.12.01.08.05.43 (version=TLSv1/SSLv3 cipher=RC4-MD5); Wed, 01 Dec 2010 08:05:43 -0800 (PST) Message-ID: <4CF6725B.2050004@logicmonitor.com> Date: Wed, 01 Dec 2010 08:05:47 -0800 From: Steve Francis User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.12) Gecko/20101027 Lightning/1.0b2 Thunderbird/3.1.6 MIME-Version: 1.0 To: pgsql-admin@postgresql.org Subject: Re: Best Linux filesystem for Postgres data store ? References: <4CF61B430200002500038009@gw.wicourts.gov> In-Reply-To: <4CF61B430200002500038009@gw.wicourts.gov> X-Enigmail-Version: 1.1.1 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.876 tagged_above=-10 required=5 tests=BAYES_00=-1.9, HTML_MESSAGE=0.001, MIME_HTML_ONLY=0.723, RCVD_IN_DNSWL_LOW=-0.7 X-Spam-Level: X-Archive-Number: 201012/5 X-Sequence-Number: 36234 On 12/1/2010 7:54 AM, Kevin Grittner wrote:

 
Your RAID configuration and controllers will likely make a bigger
difference than your filesystem choices.  Be sure to get good RAID
controllers with battery-backed (BBU) cache, configured for
write-back.

I agree that storage makes a bigger difference than filesystems in most cases.
Just wanted to jump in and say that testing with your workload is really the only way to know things for sure. (Obviously, more spindles implies more IOps, more cache implies faster writes...)
But I have seen cases where a dell PERC RAID controller (not sure that qualifies as "good") slowed things down when configured for writeback with a write heavy workload. We noticed very spiky disk IO rates on some database servers (we are monitoring company, so have lots and lots of pretty graphs.) The controller seemed to accept a bunch of writes quickly, then when full then try to pump them all to disk, which took a non-trivial number of seconds. So we'd see the interesting state of iostat reporting zero disk transactions per second, but busy time = 100% and service time being hundreds of millseconds.
Switching to write through made things much faster overall. Not what I expected.

This was a PERC 5, so a few years ago. No doubt things have improved, but the point is to test and monitor.

Steve Francis		LogicMonitor LLC

sfrancis@logicmonitor.com www.logicmonitor.com		Ph: 1 888 41 LOGIC x500 Ph: 1 805 698 0770