From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265700AbUBPRME (ORCPT ); Mon, 16 Feb 2004 12:12:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265682AbUBPRME (ORCPT ); Mon, 16 Feb 2004 12:12:04 -0500 Received: from kinesis.swishmail.com ([209.10.110.86]:1798 "EHLO kinesis.swishmail.com") by vger.kernel.org with ESMTP id S265900AbUBPRKv (ORCPT ); Mon, 16 Feb 2004 12:10:51 -0500 Message-ID: <4030FB66.6060803@techsource.com> Date: Mon, 16 Feb 2004 12:18:30 -0500 From: Timothy Miller MIME-Version: 1.0 To: Daniel Blueman CC: aradford@3WARE.com, linux-kernel@vger.kernel.org Subject: Re: File system performance, hardware performance, ext3, 3ware RA ID1, etc. References: <402D6354.3010801@techsource.com> <30156.1076775952@www12.gmx.net> In-Reply-To: <30156.1076775952@www12.gmx.net> 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 Daniel Blueman wrote: > Tim, > > Do you get the same numbers (but slightly higher, as this is will measure > from a smaller portion of outer zones) with: > > # hdparm -t /dev/sda > > ? I ran this test. This is a read test. What I did below was a write test. Additionally, I ran this test: time dd if=/dev/sda of=/dev/null bs=1024k count=1024 From that, I got 47 megs/sec. From 'hdparm -t /dev/sda', I got a slightly lower number. So, for reads, I'm getting good performance. 47 megs/sec at the outer-most tracks is a bit lower than the 50+ that reviewers report, but it's not bad. However, I don't get anywhere near the 40+ megs/sec the reviewers say the drive gets for writes. That model as a single drive in my wife's computer gets about 39 megs/sec, which is great. But behind the 3ware, the drive gets only 13 megs/sec. (iozone reports about 15 megs/sec, but that's influenced by caching in RAM, and iozone is writing to a file on tracks further out, I think.) > > >>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. > >