Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id 9B97C1337B3E for ; Thu, 28 Apr 2011 21:13:10 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia, port 10024) with ESMTP id 15501-04 for ; Fri, 29 Apr 2011 00:13:03 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.17.8]) by mail.postgresql.org (Postfix) with ESMTP id 3E7E71336FA7 for ; Thu, 28 Apr 2011 21:13:03 -0300 (ADT) Received: from [192.168.1.6] (mail.highperformancepostgresql.com [71.179.240.8]) by mrelayeu.kundenserver.de (node=mreu4) with ESMTP (Nemesis) id 0M6K5P-1PrMHM0KEd-00yR9m; Fri, 29 Apr 2011 02:13:03 +0200 Message-ID: <4DBA02D8.4050705@2ndQuadrant.com> Date: Thu, 28 Apr 2011 20:14:16 -0400 From: Greg Smith User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20110307 Icedove/3.0.11 MIME-Version: 1.0 To: pgsql-performance@postgresql.org Subject: Re: VX_CONCURRENT flag on vxfs( 5.1 or later) for performance for postgresql? References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V02:K0:3CHEDhr9WbCF3MNXw/FhvSEmNqdVOf6iFzNG7OvZxaG Blx4Rw0oLJDOg7bhIxVqyxkgHijm6APb2zVgxoN8LiBDM7ImDz wI4iGAZJ1AN4ul21NJxCLqMl4rB0jKW5vNXsFdWo4p7bgjDKZB kN+Y6RkqekkuVf4J8cVIEWttd3p2VuDfJzY4RC//PTtmd3yNOV OMeYlU4FBer2AfaSz67IVuzA4Hjs8f2U5bbbzTUupU= X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.9 tagged_above=-10 required=5 tests=BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001 X-Spam-Level: X-Archive-Number: 201104/397 X-Sequence-Number: 43459 On 04/27/2011 11:33 PM, HSIEN-WEN CHU wrote: > When database files are on a VxFS filesystem, performance can be > significantly improved by setting the VX_CONCURRENT cache advisory on > the file according to vxfs document, > That won't improve performance, and it's not safe either. VX_CONCURRENT switches the filesystem to use direct I/O. That's usually slower for PostgreSQL. And it introduces some requirements for both block alignment and the application avoiding overlapping writes. PostgreSQL doesn't do either, so I wouldn't expect it to be compatible with VX_CONCURRENT. -- Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us