Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 21 Aug 2002 11:05:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 21 Aug 2002 11:05:56 -0400 Received: from mail4.quicken.com ([206.154.105.71]:30949 "EHLO mail4.quicken.com") by vger.kernel.org with ESMTP id ; Wed, 21 Aug 2002 11:05:54 -0400 X-Server-Uuid: A30EB3EE-CD20-42DB-89B9-CCAEC3F48615 Message-ID: <1D633A747CE4D311B89400D0B73EB16E05F00A42@liex01.liv.intuit.com> From: "Downey, Brian" To: "'Nagy Tibor'" , linux-kernel@vger.kernel.org Subject: RE: Dell Perc 3/QC performance Date: Wed, 21 Aug 2002 11:09:43 -0400 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) X-WSS-ID: 117D72BD3956159-01-01 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3927 Lines: 123 What type of RAID are you attempting to use? -Brian -----Original Message----- From: Nagy Tibor [mailto:nagyt@otpbank.hu] Sent: Wednesday, August 21, 2002 10:26 AM To: linux-kernel@vger.kernel.org Subject: Dell Perc 3/QC performance Hi, I am not satisfied with the disk I/O performance of the RAID controller 'Dell Perc 3/QC' (AMI megaraid) under Linux. Short description of my problem: We have a Dell PowerEdge 6600 + PERC 3/QC, and I am not satisfied with the performance. I/O speed is not linearly growing if I read more disks simultenausly. If I read 1 disk, I get about 49 MB/s read speed, if I read 2 disks simultaneosly I get about 64 MB/s read speed (only +15MB/s), if I read 3 disks simultaneosly I get about 68 MB/s read speed (only +4MB/s), If I read more disk I don't get higher speed. Do you have any idea, what is the problem? Detailed description: 1. Configuration Dell Poweredge 6600: 4 x 1400 MHz, 4 GB RAM PERC 3/QC Firmware: 1.61N Bios: 3.17 Logical drive 0 (18 GB) - RAID 1 - Channel 0 Id 0 - 18 GB \ Channel 0 Id 1 - 18 GB Logical drive 1 (22 GB) - RAID 1 - Channel 2 Id 0 - 72 GB Logical drive 2 (22 GB) + \ Channel 3 Id 9 - 72 GB Logical drive 3 (24 GB) / Logical drive 4 (22 GB) - RAID 1 - Channel 2 Id 1 - 72 GB Logical drive 5 (22 GB) + \ Channel 3 Id 10 - 72 GB Logical drive 6 (24 GB) / Logical drive 7 (22 GB) - RAID 1 - Channel 2 Id 2 - 72 GB Logical drive 8 (22 GB) + \ Channel 3 Id 11 - 72 GB Logical drive 9 (24 GB) / 18 GB disks: Quantum ATLAS 10KIII 18 SCA (160 MB SCSI) 72 GB disks: Hitachi DK32DJ-72 (160 MB SCSI) The 18 GB disks are installed in the server itself, the 72 GB disks are installed in a PowerVault 221S disk tower with splitted backplane. The 72 GB disks are splitted into 22-24 GB logical drives, because Informix database engine can use max 2GB chunks (partitions), and only 15 partitions can be installed in linux on 1 drive. 'Cache policy' is set to 'Direct IO' and 'Read (ahead) policy' to 'adaptive' for all logical drives. (I tried other confugurations, too.) Logical drives 1-9 are used as raw devices by informix, logical drive 0 is for the operating system. 2. Operating system SuSe Linux 8.0, kernel 2.4.18 emiir:~ # uname -a Linux emiir 2.4.18-64GB-SMP #1 SMP Wed Mar 27 13:58:12 UTC 2002 i686 unknown 3. I/O test 3.1 Read from Logical drive 1 dd if=/dev/rsdb1 of=/dev/null bs=1024k -> 49 MB/s I/O 3.2 Read from Logical drive 1 and 4 (different disks) dd if=/dev/rsdb1 of=/dev/null bs=1024k & dd if=/dev/rsde1 of=/dev/null bs=1024k & -> 64 MB/s I/O 3.2 Read from Logical drive 1, 4 and 7 (different disks) dd if=/dev/rsdb1 of=/dev/null bs=1024k & dd if=/dev/rsde1 of=/dev/null bs=1024k & dd if=/dev/rsdh1 of=/dev/null bs=1024k & -> 68 MB/s I/O All I/O speed came from the column 'bi' of 'vmstat 1'. 4. Result I do not understand, why the speed is not increased nearly linearly. The I/O between the PERC controller and the host is 64 bit PCI with 66MHz, ca. 530MB/s, each of the four SCSI channel has a speed of 160MB/s. At least test 3.2 should result the double of the speed of test 3.1 (two SCSI channel, separate disks). I see also on the dell site 300 MB/s for sequential read: http://www.dell.com/us/en/biz/topics/power_ps1q02-perc.htm Do you have any idea what can be wrong? Than you Tibor ------------------------------------------------------------------------ Tibor Nagy National Savings and Commercial Bank Ltd (OTP Bank) H-1051 Budapest Nador u. 16. Tel: 00 36 1 374 6990 Fax: 00 36 1 374 6981 E-mail: nagyt@otpbank.hu ------------------------------------------------------------------------ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/