X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 33DC811F65C0 for ; Fri, 7 Apr 2006 18:26:10 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 54408-03-3 for ; Fri, 7 Apr 2006 18:25:58 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey- Received: from fon.nation-net.com (213-2-2-26.uk.vianw.net [213.2.2.26]) by postgresql.org (Postfix) with ESMTP id B6FC911F719C for ; Fri, 7 Apr 2006 18:25:54 -0300 (ADT) Received: from fon.nation-net.com (localhost [127.0.0.1]) by fon.nation-net.com (Postfix) with ESMTP id A784713768F for ; Fri, 7 Apr 2006 22:24:47 +0100 (BST) Received: from eddie.acentral.co.uk (80-192-144-33.cable.ubr04.pres.blueyonder.co.uk [80.192.144.33]) by fon.nation-net.com (Postfix) with ESMTP id 81883137666 for ; Fri, 7 Apr 2006 22:24:47 +0100 (BST) Received: from eddie.acentral.co.uk (eddie.acentral.co.uk [127.0.0.1]) by eddie.acentral.co.uk (Postfix) with ESMTP id B42C775FE5 for ; Fri, 7 Apr 2006 22:24:49 +0100 (BST) Received: from localhost.localdomain (unknown [10.0.0.29]) by eddie.acentral.co.uk (Postfix) with SMTP id 9A72A75D0A for ; Fri, 7 Apr 2006 22:24:49 +0100 (BST) Date: Fri, 7 Apr 2006 22:24:43 +0100 From: Gavin Hamill To: pgsql-performance@postgresql.org Subject: Re: pg 8.1.3, AIX, huge box, painfully slow. Message-Id: <20060407222443.97ddf152.gdh@laterooms.com> In-Reply-To: <1144441457.32269.29.camel@state.g2switchworks.com> References: <20060407185823.abe93017.gdh@laterooms.com> <1144436060.32269.13.camel@state.g2switchworks.com> <20060407205919.a091da26.gdh@laterooms.com> <1144441457.32269.29.camel@state.g2switchworks.com> X-Mailer: Sylpheed version 2.1.1 (GTK+ 2.8.6; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV using ClamSMTP X-AV-Checked: ClamAV using ClamSMTP X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.096 required=5 tests=[AWL=0.096] X-Spam-Score: 0.096 X-Spam-Level: X-Archive-Number: 200604/157 X-Sequence-Number: 18241 On Fri, 07 Apr 2006 15:24:18 -0500 Scott Marlowe wrote: > > See reply to Tom Lane :) > > I didn't see one go by yet... Could be sitting in the queue. If it's not arrived by now - EXPLAIN ANALYZE doesn't tell me anything :) > Let us know if changing the fsync setting helps. Hopefully that's all > the problem is. fsync's already off - yes a bit scary, but our I/O is only about 500KB/sec writing.. the whole db fits in RAM / kernel disk cache, and I'd rather have performance than security at this exact moment.. > Off on a tangent. If the aggregate memory bandwidth of the pSeries is > no greater than you Xeon you might not see a big improvement if you > were memory bound before. If you were CPU bound, you may or may not > see an improvement. I did look into the specs of the system, and the memory bw on the pSeries was /much/ greater than the Xeon - it's one of the things that really pushed me towards it in the end. I forget the figures, but it was 3 or 4 times greater. > Can you describe the disc subsystems in the two machines for us? What > kind of read / write load you have? It could be the older box was > running on IDE drives with fake fsync responses which would lie, be > fast, but not reliable in case of a power outage. Again, I'm confident that I/O's not the killer here.. the Xeon is a Dell 6850- hardware RAID1.. SCSI drives. > > Multi-Opteron was the other thing we considered but decided to give > > 'Big Iron' UNIX a whirl... > > It still might be a good choice, if it's a simple misconfiguration > issue. > > But man, those new multiple core opterons can make some impressive > machines for very little money. So I see - we could buy two quad-opterons for the cost of renting this pSeries for a month.... Cheers, Gavin.