Received: from maia.hub.org (maia-5.hub.org [200.46.204.29]) by mail.postgresql.org (Postfix) with ESMTP id 9F32D1337B2F for ; Sun, 13 Feb 2011 19:23:29 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.29]) (amavisd-maia, port 10024) with ESMTP id 52683-04 for ; Sun, 13 Feb 2011 23:23:23 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.126.186]) by mail.postgresql.org (Postfix) with ESMTP id A8DE81337999 for ; Sun, 13 Feb 2011 19:23:21 -0400 (AST) Received: from [192.168.1.6] (mail.highperformancepostgresql.com [71.179.240.8]) by mrelayeu.kundenserver.de (node=mrbap1) with ESMTP (Nemesis) id 0LbxSO-1QXxOO3q7w-00jWDS; Mon, 14 Feb 2011 00:23:21 +0100 Message-ID: <4D5867E7.1090409@2ndquadrant.com> Date: Sun, 13 Feb 2011 18:23:19 -0500 From: Greg Smith User-Agent: Thunderbird 2.0.0.24 (X11/20100317) MIME-Version: 1.0 To: sergey CC: pgsql-performance@postgresql.org Subject: Re: choosing the right RAID level for PostgresQL database References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V02:K0:PXsPkxPYiVKS8sNr4Ahu+Og/4cEAFb1YVdqvtw+YhZN 9Ux7+uwgPlNUjnSxWjhLIYEdof7I+NKiF41CG803SzS94040Zv xxqKE4el+WJWpU6XWUZYBY9wrAPwASQHKS2YqMbUhcFD3kJwTt VUh/5/0rDFAdBcfDn52tFTDE60XrmQ32Et0JEINTLPj77t5oSZ ULuoBfFVdYMrYJrkSBv5L34Vhg0jjnPSG5sbAAX8bo= 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: 201102/361 X-Sequence-Number: 42499 sergey wrote: > I got a disk array appliance of 8 disks 1T each (UltraStor RS8IP4). It > will be used solely by PostgresQL database and I am trying to choose > the best RAID level for it. > .. > Space is the least important factor. Even 1T will be enough. Use RAID10, measure the speed of the whole array using the bonnie++ ZCAV tool, and only use the fastest part of each array to store the important stuff. You will improve worst-case performance in both sequential reads and seek time that way. Drives are nearly twice as fast at their beginning as they are at the end, and with only 8 drives you should be able to setup a RAID10 array with all the fast parts aligned. -- Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us "PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books