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 B16669DC861 for ; Tue, 31 Jan 2006 19:13:16 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 83325-05 for ; Tue, 31 Jan 2006 19:13:18 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from mail.Mi8.com (d01gw01.mi8.com [63.240.6.47]) by postgresql.org (Postfix) with ESMTP id 6A6819DC827 for ; Tue, 31 Jan 2006 19:13:14 -0400 (AST) Received: from 172.16.1.110 by mail.Mi8.com with ESMTP (- Welcome to Mi8 Corporation www.Mi8.com (D1)); Tue, 31 Jan 2006 18:13:12 -0500 X-Server-Uuid: 241911D6-425B-44B9-A073-E3FE0F8FC774 Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by D01SMTP01.Mi8.com with Microsoft SMTPSVC(6.0.3790.1830); Tue, 31 Jan 2006 18:13:12 -0500 Received: from 67.103.45.218 ([67.103.45.218]) by MI8NYCMAIL06.Mi8.com ( [172.16.1.219]) via Exchange Front-End Server mi8owa.mi8.com ( [172.16.1.106]) with Microsoft Exchange Server HTTP-DAV ; Tue, 31 Jan 2006 23:13:11 +0000 User-Agent: Microsoft-Entourage/11.2.1.051004 Date: Tue, 31 Jan 2006 15:13:10 -0800 Subject: Re: Huge Data sets, simple queries From: "Luke Lonergan" To: "PFC" , "Jeffrey W. Baker" , pgsql-performance@postgresql.org Message-ID: Thread-Topic: [PERFORM] Huge Data sets, simple queries Thread-Index: AcYmu+bTJSLNLJKvEdqBvAANk63kWA== In-Reply-To: MIME-Version: 1.0 X-OriginalArrivalTime: 31 Jan 2006 23:13:12.0227 (UTC) FILETIME=[E8275730:01C626BB] X-WSS-ID: 6FC1308232K1830268-01-01 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=1.309 required=5 tests=[AWL=0.056, RCVD_NUMERIC_HELO=1.253] X-Spam-Score: 1.309 X-Spam-Level: * X-Archive-Number: 200601/498 X-Sequence-Number: 16976 PFC, On 1/31/06 3:11 PM, "PFC" wrote: >> ... Prove it. >> > > (I have a software RAID1 on this desktop machine) > > It's a lot faster than a single disk for random reads when more than 1 > thread hits the disk, because it distributes reads to both disks. Thus, > applications start faster, and the machine is more reactive even when the > disk is thrashing. Cron starting a "updatedb" is less painful. It's cool > for desktop use (and of course it's more reliable). Exactly - improved your random seeks. > However large reads (dd-style) are just the same speed as 1 drive. I > guess you'd need a humongous readahead in order to read from both disks. Nope - won't help. - Luke