Received: from localhost (maia-3.hub.org [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id 81C8E9FBD26 for ; Thu, 28 Jun 2007 05:03:55 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 85399-05 for ; Thu, 28 Jun 2007 05:03:48 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from mail.metronet.co.uk (mail.metronet.co.uk [213.162.97.75]) by postgresql.org (Postfix) with ESMTP id F20689FA65C for ; Thu, 28 Jun 2007 05:03:51 -0300 (ADT) Received: from server3.office.archonet.com (84-51-143-99.archon037.adsl.metronet.co.uk [84.51.143.99]) by smtp.metronet.co.uk (MetroNet Mail) with ESMTP id 9AF3E1438BD; Thu, 28 Jun 2007 09:03:50 +0100 (BST) Received: from [192.168.1.36] (dell36.office.archonet.com [192.168.1.36]) by server3.office.archonet.com (Postfix) with ESMTP id 7D06E2740E6; Thu, 28 Jun 2007 09:03:57 +0100 (BST) Message-ID: <46836B66.7050109@archonet.com> Date: Thu, 28 Jun 2007 09:03:50 +0100 From: Richard Huxton User-Agent: Thunderbird 2.0.0.0 (X11/20070326) MIME-Version: 1.0 To: Ho Fat Tsang Cc: pgsql-performance@postgresql.org Subject: Re: PostgreSQL 8.0 occasionally slow down References: <97e6e20f0706272354m5e42c91em177c8b80abb2ea52@mail.gmail.com> <468361A9.1040308@archonet.com> <97e6e20f0706280101y543b871ao4cbf85e57f07f7e9@mail.gmail.com> In-Reply-To: <97e6e20f0706280101y543b871ao4cbf85e57f07f7e9@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200706/624 X-Sequence-Number: 25657 Ho Fat Tsang wrote: > Hi Richard, > > I have tuned the checkpoint_timeout to 30 second which is ten times less > than default and the issue is still reproduced. Do you have any recommended > configuration for WAL ? If you look at the output of "vmstat 10" and "iostat -m 10" (I'm assuming you're on Linux) does it show your I/O peaking every three minutes? I might have been wrong about the cause. -- Richard Huxton Archonet Ltd