X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (unknown [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 3B21E528DA for ; Wed, 17 Aug 2005 13:49:36 -0300 (ADT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 52195-05 for ; Wed, 17 Aug 2005 16:49:34 +0000 (GMT) Received: from mail24.sea5.speakeasy.net (mail24.sea5.speakeasy.net [69.17.117.26]) by svr1.postgresql.org (Postfix) with ESMTP id 227385288A for ; Wed, 17 Aug 2005 13:49:33 -0300 (ADT) Received: (qmail 27532 invoked from network); 17 Aug 2005 16:49:33 -0000 Received: from dsl081-060-184.sfo1.dsl.speakeasy.net (HELO noodles) ([64.81.60.184]) (envelope-sender ) by mail24.sea5.speakeasy.net (qmail-ldap-1.03) with RC4-MD5 encrypted SMTP for ; 17 Aug 2005 16:49:33 -0000 Subject: Re: Need for speed From: "Jeffrey W. Baker" To: Ulrich Wisser Cc: pgsql-performance@postgresql.org In-Reply-To: <4303003B.3020407@relevanttraffic.se> References: <4303003B.3020407@relevanttraffic.se> Content-Type: text/plain Date: Wed, 17 Aug 2005 09:49:37 -0700 Message-Id: <1124297377.423.2.camel@noodles> Mime-Version: 1.0 X-Mailer: Evolution 2.2.1.1 Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0 required=5 tests=[none] X-Spam-Level: X-Archive-Number: 200508/206 X-Sequence-Number: 13953 On Wed, 2005-08-17 at 11:15 +0200, Ulrich Wisser wrote: > Hello, > > thanks for all your suggestions. > > I can see that the Linux system is 90% waiting for disc io. At that time > all my queries are *very* slow. My scsi raid controller and disc are > already the fastest available. What RAID controller? Initially you said you have only 2 disks, and since you have your xlog on a separate spindle, I assume you have 1 disk for the xlog and 1 for the data. Even so, if you have a RAID, I'm going to further assume you are using RAID 1, since no sane person would use RAID 0. In those cases you are getting the performance of a single disk, which is never going to be very impressive. You need a RAID. Please be more precise when describing your system to this list. -jwb