Received: from makus.postgresql.org (makus.postgresql.org [98.129.198.125]) by mail.postgresql.org (Postfix) with ESMTP id 5FBDFC32C6B for ; Fri, 23 Mar 2012 04:11:06 -0300 (ADT) Received: from mail-we0-f174.google.com ([74.125.82.174]) by makus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1SAyeP-0005ST-BD for pgsql-performance@postgresql.org; Fri, 23 Mar 2012 07:11:05 +0000 Received: by wejx9 with SMTP id x9so2421919wej.19 for ; Fri, 23 Mar 2012 00:10:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=mAOn/vrqQGoOYQD6JF5YBk6VomMML4+G4bZrV39wDr8=; b=Mdc+du08TUn4jBBBKr9XdkP690AGllIZhPPvkIscOuLBjKm8VTEobU4FYPk0qpKLfx NQ3sDMG6CPWOi/InBLPmu64TEBD+ZYaWOSwpdN+F+xclu8JmubUfbOzMfbJHcLbj9+Qy rMjvS0wTR6eE0U0WwNqcS9iIJC7+2EkcKbo9EJ3R0j01c+6lCF1xrYxxTkiW1RoQd4MT gADd5A6bwcPb9/psjyDBaefWBPz3FV2vsQOSCidt+v3RD3faJhWDu7s+wWulF3uA0rgY c2si6VxlhUYSS1xLdnbtpD5s3Xe05J2OPW8vKrRpcacvGiYQDUJeyBw5Qb9tB9+ktlCU rlrQ== Received: by 10.216.132.40 with SMTP id n40mr6302694wei.68.1332486651856; Fri, 23 Mar 2012 00:10:51 -0700 (PDT) Received: from [192.168.73.63] (5357DA75.cm-6-8d.dynamic.ziggo.nl. [83.87.218.117]) by mx.google.com with ESMTPS id gd4sm6778092wib.6.2012.03.23.00.10.49 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 23 Mar 2012 00:10:50 -0700 (PDT) Message-ID: <4F6C21ED.903@gmail.com> Date: Fri, 23 Mar 2012 08:10:37 +0100 From: Yeb Havinga User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2 MIME-Version: 1.0 To: Sebastian Melchior CC: Scott Marlowe , pgsql-performance@postgresql.org Subject: Re: Sudden Query slowdown on our Postgresql Server References: <03615FD7-20B3-49AB-AC5E-484544D03933@mailz.de> <20120323004749.GG3938@tamriel.snowman.net> <08416066-2163-4D4F-AEE9-93FEDECD1CC3@mailz.de> In-Reply-To: <08416066-2163-4D4F-AEE9-93FEDECD1CC3@mailz.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: -2.6 (--) X-Archive-Number: 201203/157 X-Sequence-Number: 46607 On 2012-03-23 05:53, Sebastian Melchior wrote: > Hi, > > we already used iostat and iotop during times of the slowdown, there is no sudden drop in I/O workload in the times of the slowdown. Also the iowait does not spike and stays as before. > So i do not think that this is I/O related. As the disks are SSDs there also still is some "head room" left. I've seen a ssd completely lock up for a dozen seconds or so after giving it a smartctl command to trim a section of the disk. I'm not sure if that was the vertex 2 pro disk I was testing or the intel 710, but enough reason for us to not mount filesystems with -o discard. regards, Yeb