Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id E37CC1337B5C for ; Wed, 16 Feb 2011 16:56:23 -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 85836-05 for ; Wed, 16 Feb 2011 20:56:15 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.17.10]) by mail.postgresql.org (Postfix) with ESMTP id 349F21337B4E for ; Wed, 16 Feb 2011 16:56:15 -0400 (AST) Received: from [192.168.1.6] (mail.highperformancepostgresql.com [71.179.240.8]) by mrelayeu.kundenserver.de (node=mreu0) with ESMTP (Nemesis) id 0LnFtp-1QHhS71Ubt-00hKE0; Wed, 16 Feb 2011 21:56:14 +0100 Message-ID: <4D5C39ED.9040609@2ndquadrant.com> Date: Wed, 16 Feb 2011 15:56:13 -0500 From: Greg Smith User-Agent: Thunderbird 2.0.0.24 (X11/20100317) MIME-Version: 1.0 To: Bryan Keller CC: pgsql-admin@postgresql.org Subject: Re: Postgres on NAS/NFS References: <9424C7B4-672D-4C64-BE6A-699708981C0B@gmail.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V02:K0:L3Pk4oLXrg83KnPDl8miJ1CPQ+ceB2tvh7uHtL35kb+ ZzBrG5OOWEgcIAsUQMYecWeb62tbTGvu9qaEokrh283RqLy04U Vzk2aeOz35V3i/SbEF/EuhRdhaUU4pfqEDGC6QiPEBvLI9DpO9 hPBgdO013ltUOrdyETnYYCvVro5HyHKRRcjzxsq+rPcmdED/2A /8jzh3DrIFW3bmadQQwPBKBmeLU8ILWaEfQZAerueQ= 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: 201102/154 X-Sequence-Number: 36793 Bryan Keller wrote: > It sounds like NFS is a viable solution nowadays. I a still going to shoot for using iSCSI, given it is a block-level protocol rather than file-level, it seems to me it would be better suited to database I/O. > Please digest carefully where Joe Conway pointed out that it took them major kernel-level work to get NFS working reliably on Linux. On anything but Solaris, I consider NFS a major risk still; nothing has improved "nowadays" relative to when people used to report regular database corruption running it on other operating systems. Make sure you read http://www.time-travellers.org/shane/papers/NFS_considered_harmful.html and mull over the warnings in there before you assume it will work, too. I don't think I've ever heard from someone happy with an iSCSI deployment, either. The only way you could make an NFS+iSCSI storage solution worse is to also use RAID5 on the NAS. I'd suggest taking a look at http://wiki.postgresql.org/wiki/Shared_Storage and consider how you're going to handle fencing issues as well here. One of the reasons SANs tend to be preferred in this area is because fencing at the fiber-channel switch level is pretty straightforward. DAS running over fiber-channel can offer the same basic features though, it's just not as common to use a switch in that environment. -- 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