Received: from magus.postgresql.org ([87.238.57.229]) by malur.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1TLMYc-0006aR-Ss for pgsql-performance@postgresql.org; Mon, 08 Oct 2012 23:16:18 +0000 Received: from [2001:1528:137::f1] (helo=mail.gransy.com) by magus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1TLMYc-0002zf-0c for pgsql-performance@postgresql.org; Mon, 08 Oct 2012 23:16:18 +0000 Received: from antispam.gransy.com (antispam.gransy.com [77.78.104.124]) by mail.gransy.com (Postfix) with ESMTP id E6A00508A36 for ; Tue, 9 Oct 2012 01:16:14 +0200 (CEST) Received: from mail.gransy.com ([82.208.44.189]) by antispam.gransy.com (antispam.gransy.com [77.78.104.124]) (amavisd-new, port 10024) with ESMTP id UisZH-TwsoUK for ; Tue, 9 Oct 2012 01:16:14 +0200 (CEST) Received: by mail.gransy.com (Postfix, from userid 5000) id D2287508A47; Tue, 9 Oct 2012 01:16:14 +0200 (CEST) Received: from [192.168.1.237] (ip-78-45-133-255.net.upcbroadband.cz [78.45.133.255]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.gransy.com (Postfix) with ESMTPSA id AFCAF508A36 for ; Tue, 9 Oct 2012 01:16:14 +0200 (CEST) Message-ID: <50735EBF.5010909@fuzzy.cz> Date: Tue, 09 Oct 2012 01:16:15 +0200 From: Tomas Vondra User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120907 Thunderbird/15.0.1 MIME-Version: 1.0 To: pgsql-performance@postgresql.org Subject: Re: Two identical systems, radically different performance References: <4CB0E3B6-CF1E-4B54-9900-E8356744F0AA@gmail.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2001:1528:137::f1 (failed) X-Pg-Spam-Score: -1.1 (-) X-Archive-Number: 201210/76 X-Sequence-Number: 48035 On 9.10.2012 01:03, Craig James wrote: > > > On Mon, Oct 8, 2012 at 3:50 PM, Claudio Freire > wrote: > > On Mon, Oct 8, 2012 at 7:48 PM, Craig James > wrote: > >> > # blockdev --getra /dev/sdb1 > >> > 256 > >> > >> > >> It's probably this. 256 is way too low to saturate your I/O system. > >> Pump it up. I've found 8192 works nice for a system I have, 32000 I > >> guess could work too. > > > > > > But again ... the two systems are identical. This can't explain it. > > Is the read-ahead the same in both systems? > > > Yes, as I said in the original reply (it got cut off from your reply): > "Same on both servers." And what about read-ahead settings on the controller? 3WARE used to have a read-ahead settings on their own (usually there are three options - read-ahead, no read-ahead and adaptive). Is this set to the same value on both machines? Tomas