From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267270AbUBMWue (ORCPT ); Fri, 13 Feb 2004 17:50:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267271AbUBMWuU (ORCPT ); Fri, 13 Feb 2004 17:50:20 -0500 Received: from kinesis.swishmail.com ([209.10.110.86]:50185 "EHLO kinesis.swishmail.com") by vger.kernel.org with ESMTP id S267270AbUBMWtq (ORCPT ); Fri, 13 Feb 2004 17:49:46 -0500 Message-ID: <402D5628.6070705@techsource.com> Date: Fri, 13 Feb 2004 17:56:40 -0500 From: Timothy Miller MIME-Version: 1.0 To: Daniel Blueman CC: linux-kernel@vger.kernel.org Subject: Re: File system performance, hardware performance, ext3, 3ware RAID1, etc. References: <9792.1076675029@www11.gmx.net> In-Reply-To: <9792.1076675029@www11.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: > Willy Tarreau wrote in message > news:<1oEGw-2ex-1@gated-at.bofh.it>... > >>On Thu, Feb 12, 2004 at 06:32:31PM -0500, Timothy Miller wrote: >> >> >>>For writes, iozone found an upper bound of about 10megs/sec, which is >>>abysmal. Typically, I'd expect writes to be faster (on a single drive) >>>than reads, because once the write is sent, you can forget about it. >>>You don't have to wait around for something to come back, and that >>>latency for reads can hurt performance. The OS can also buffer writes >>>and reorder them in order to improve efficiency. >> >>It depends on the disk too. Lots of disks (specially IDE) are far slower >>on writes than they are on reads. > > > No. Have you verified this? If you 'dd' your swap partition from /dev/zero > on IDE, you'll see write performance closely matches read performance, for > drives old and new. > And this sort of things is what I find with raw writes to the model of drive I'm using. However, it seems that there must be some issue with the 3ware 7000-2 which is killing performance, or the way the Linux kernel is dealing with this sorta-SCSI device. The WD1200JB should get like 30-40 megs/sec, but when being accessed through the 3ware, I get 10-16 megs/sec. What could the 3ware be doing?