From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267232AbUBMXqE (ORCPT ); Fri, 13 Feb 2004 18:46:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267237AbUBMXqD (ORCPT ); Fri, 13 Feb 2004 18:46:03 -0500 Received: from kinesis.swishmail.com ([209.10.110.86]:18445 "EHLO kinesis.swishmail.com") by vger.kernel.org with ESMTP id S267232AbUBMXp4 (ORCPT ); Fri, 13 Feb 2004 18:45:56 -0500 Message-ID: <402D6354.3010801@techsource.com> Date: Fri, 13 Feb 2004 18:52:52 -0500 From: Timothy Miller MIME-Version: 1.0 To: Adam Radford CC: Daniel Blueman , linux-kernel@vger.kernel.org Subject: Re: File system performance, hardware performance, ext3, 3ware RA ID1, etc. References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Adam Radford wrote: > Perhaps you are issuing non purely sequential IO. The card firmware does > some > reodering, but at some point it will cause performance degradation. Can you > try > kernel 2.6 w/xfs? Not any time soon, but as I mentioned earlier, I measured 13.9 megs/sec when I ran this command: time dd if=/dev/zero of=/dev/sda2 bs=1024k count=1024 No file system was involved; I was simply writing zeros to the block device (swap partition with swap off). It took 73.522 seconds to do the above operation. Also, I was running in single-user mode while doing the test. > > Also, in my experience, the 'raw io' interface doesn't issue any > asynchronous IO. The > card _definately_ needs asynchronous IO posted to it or you will not get > good results > because you won't get all the drives busy. With RAID1, both drives will be written with the same data. There is no need to be asynchronous, since it's all completely linear and sequential with large data blocks.