Received: from maia.hub.org (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id C2100637D59 for ; Thu, 14 Jan 2010 10:49:47 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 16855-01 for ; Thu, 14 Jan 2010 14:49:36 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from marajade.localdomain (vcs5.camavision.com [63.228.164.252]) by mail.postgresql.org (Postfix) with ESMTP id 3ACE5634F82 for ; Thu, 14 Jan 2010 10:49:37 -0400 (AST) Received: from [192.168.10.85] (unknown [192.168.10.85]) (Authenticated sender: andy) by marajade.localdomain (Postfix) with ESMTPA id 36AF5A403C; Thu, 14 Jan 2010 08:49:35 -0600 (CST) Message-ID: <4B4F2F00.7070401@squeakycode.net> Date: Thu, 14 Jan 2010 08:49:36 -0600 From: Andy Colson User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.5) Gecko/20091204 Thunderbird/3.0 MIME-Version: 1.0 To: Craig Ringer , pgsql-performance@postgresql.org Subject: Re: a heavy duty operation on an "unused" table kills my server References: <4B4D5698.8040808@emolecules.com> <4B4D61DA.7080008@postnewspapers.com.au> <603c8f071001130823l69804fe3m5c6fbb081c55c265@mail.gmail.com> <4B4EAD76.9030305@postnewspapers.com.au> In-Reply-To: <4B4EAD76.9030305@postnewspapers.com.au> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=3.189 tagged_above=-10 required=5 tests=BAYES_50=0.001, FH_DATE_PAST_20XX=3.188 X-Spam-Level: *** X-Archive-Number: 201001/273 X-Sequence-Number: 37153 On 1/13/2010 11:36 PM, Craig Ringer wrote: > Robert Haas wrote: > >> I'm kind of surprised that there are disk I/O subsystems that are so >> bad that a single thread doing non-stop I/O can take down the whole >> server. Is that normal? > > No. > >> Does it happen on non-Windows operating >> systems? > > Yes. My 3ware 8500-8 on a Debian Sarge box was so awful that launching a > terminal would go from a 1/4 second operation to a 5 minute operation > under heavy write load by one writer. I landed up having to modify the > driver to partially mitigate the issue, but a single user on the > terminal server performing any sort of heavy writing would still > absolutely nuke performance. On a side note, on linux, would using the deadline scheduler resolve that? -Andy