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 DDD1D52910 for ; Fri, 22 Jul 2005 16:29:25 -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 80971-10 for ; Fri, 22 Jul 2005 19:29:16 +0000 (GMT) Received: from mail.Mi8.com (mail.mi8.com [63.240.6.50]) by svr1.postgresql.org (Postfix) with ESMTP id C9F4152917 for ; Fri, 22 Jul 2005 16:29:12 -0300 (ADT) Received: from 172.16.1.112 by mail.Mi8.com with ESMTP (- GW05 Welcome to Mi8 Corporation www.Mi8.com); Fri, 22 Jul 2005 15:28:46 -0400 X-Server-Uuid: E0C866E6-C6CD-48B5-AE61-E57E73CF3CC7 Received: from MI8NYCMAIL06.Mi8.com ([172.16.1.175]) by D01SMTP02.Mi8.com with Microsoft SMTPSVC(6.0.3790.211); Fri, 22 Jul 2005 15:28:45 -0400 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 ( [172.16.1.104]) with Microsoft Exchange Server HTTP-DAV ; Fri, 22 Jul 2005 15:28:45 -0500 User-Agent: Microsoft-Entourage/11.1.0.040913 Date: Fri, 22 Jul 2005 12:28:43 -0700 Subject: Re: [PATCHES] COPY FROM performance improvements From: "Luke Lonergan" To: "Joshua D. Drake" , "Patrick Welche" Cc: "Mark Wong" , pgsql-performance@postgresql.org, maryedie@osdl.org Message-ID: In-Reply-To: <42E128BD.2000104@commandprompt.com> MIME-Version: 1.0 X-OriginalArrivalTime: 22 Jul 2005 19:28:45.0806 (UTC) FILETIME=[93D0D0E0:01C58EF3] X-WSS-ID: 6EFF97671M810283011-02-01 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=1.574 tagged_above=0 required=5 tests=AWL, FORGED_RCVD_HELO, RCVD_NUMERIC_HELO X-Spam-Level: * X-Archive-Number: 200507/364 X-Sequence-Number: 13605 Joshua, On 7/22/05 10:11 AM, "Joshua D. Drake" wrote: > The database server is a PE (Power Edge) 6600 > > Database Server IO: > > [root@master root]# /sbin/hdparm -tT /dev/sda > > /dev/sda: > Timing buffer-cache reads: 1888 MB in 2.00 seconds = 944.00 MB/sec > Timing buffered disk reads: 32 MB in 3.06 seconds = 10.46 MB/sec > > Second Database Server IO: > > [root@pq-slave root]# /sbin/hdparm -tT /dev/sda > > /dev/sda: > Timing buffer-cache reads: 1816 MB in 2.00 seconds = 908.00 MB/sec > Timing buffered disk reads: 26 MB in 3.11 seconds = 8.36 MB/sec > [root@pq-slave root]# Can you post the "time dd if=/dev/zero of=bigfile bs=8k count=500000" results? Also do the reverse (read the file) with "time dd if=bigfile of=/dev/null bs=8k". I think you are observing what we've known for a while, hardware RAID is horribly slow. We've not found a hardware RAID adapter of this class yet that shows reasonable read or write performance. The Adaptec 2400R or the LSI or others have terrible internal I/O compared to raw SCSI with software RAID, and even the CPU usage is higher on these cards while doing slower I/O than linux SW RAID. Notably - we've found that the 3Ware RAID controller does a better job than the low end SCSI RAID at HW RAID support, and also exports JBOD at high speeds. If you export JBOD on the low end SCSI RAID adapters, the performance is also very poor, though generally faster than using HW RAID. - Luke