Received: from maia.hub.org (maia-5.hub.org [200.46.204.29]) by mail.postgresql.org (Postfix) with ESMTP id 7D09863161C for ; Wed, 28 Apr 2010 22:12:23 -0300 (ADT) 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 15009-07 for ; Thu, 29 Apr 2010 01:12:16 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.126.171]) by mail.postgresql.org (Postfix) with ESMTP id 4BFE06344AF for ; Wed, 28 Apr 2010 22:12:16 -0300 (ADT) Received: from [192.168.0.105] (pool-96-244-14-10.bltmmd.fios.verizon.net [96.244.14.10]) by mrelayeu.kundenserver.de (node=mreu0) with ESMTP (Nemesis) id 0M7Ws7-1NDnVE3bp1-00wvtf; Thu, 29 Apr 2010 03:12:12 +0200 Message-ID: <4BD8DCEA.2020003@2ndquadrant.com> Date: Wed, 28 Apr 2010 21:12:10 -0400 From: Greg Smith User-Agent: Thunderbird 2.0.0.24 (X11/20100317) MIME-Version: 1.0 To: Anj Adu CC: pgsql-admin@postgresql.org Subject: Re: more 10K disks or less 15K disks References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Provags-ID: V01U2FsdGVkX1+69noZpjPhzQBWSt8e96piU9Lqpo9XzTyVzz7 DcCsZmHFBdKbfZe1ObLXtGCfJeh6J5GdzU9nXkDHLdCQMvb8FO RPO1vu8fMkeWgp1i1hP24yGAC3htQgm X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.452 tagged_above=-10 required=5 tests=AWL=0.448, BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001 X-Spam-Level: X-Archive-Number: 201004/345 X-Sequence-Number: 34439 Anj Adu wrote: > I am faced with a hardware choice for a postgres data warehouse > (extremely high volume inserts..over 200 million records a day) That's an average of 2314 per second, which certainly isn't easy to pull off. You suggested you're already running this app. Do you have any idea how high the volume of data going to the WAL is relative to everything else? > 12 x 600G disks (15K) (the new Dell Poweredge C server) > or > 24 x 600G (10K disks) > You can expect the 15K disks to be 30% (more sequential work) to 50% (random/commit work) faster than a similar 10K drive. So from most perspectives, twice as many 10K drives should be considerably faster. The main point of concern here is the commit rate, which you can't necessarily improve just by throwing drives at it. That's based on how fast the drives spin, so there's the potential to discover a 50% regression there compared to the setup you have right now. With the RAID card in there, it should be fine, but it's something to be concerned about. Also, you didn't mentioned the RAID card for the new system, and whether it would be the same in both setups or not. That can be as important as the drives when you have larger arrays. The LSI Megaraid card Dell is using for the Perc6i is quite fast, and you'll need to make sure you get something just as good for the new server. -- Greg Smith 2ndQuadrant US Baltimore, MD PostgreSQL Training, Services and Support greg@2ndQuadrant.com www.2ndQuadrant.us