From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267281AbUBMXHZ (ORCPT ); Fri, 13 Feb 2004 18:07:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267292AbUBMXHZ (ORCPT ); Fri, 13 Feb 2004 18:07:25 -0500 Received: from kinesis.swishmail.com ([209.10.110.86]:58378 "EHLO kinesis.swishmail.com") by vger.kernel.org with ESMTP id S267281AbUBMXHT (ORCPT ); Fri, 13 Feb 2004 18:07:19 -0500 Message-ID: <402D5A46.4090409@techsource.com> Date: Fri, 13 Feb 2004 18:14:14 -0500 From: Timothy Miller MIME-Version: 1.0 To: Willy Tarreau CC: Linux Kernel Mailing List Subject: Re: File system performance, hardware performance, ext3, 3ware RAID1, etc. References: <402C0D0F.6090203@techsource.com> <20040213055350.GG29363@alpha.home.local> <402D235F.7030401@techsource.com> <20040213223949.GA13937@alpha.home.local> In-Reply-To: <20040213223949.GA13937@alpha.home.local> 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 Willy Tarreau wrote: > On Fri, Feb 13, 2004 at 02:19:59PM -0500, Timothy Miller wrote: > > >>Assuming that the "buffered" speeds are being buffered by the OS, we'll >>ignore those. I am therefore observing that the writes to a single >>drive are 3 to 4 times faster than they are through the RAID controller, >>even with the 3ware write cache ON. >> >>Does that make any sense? > > > Well, it reminds me a disk I had problems with several years ago. It had > a few defects in the FAT area, which were relocated at the end. Performance > was terrible since the head had to move constantly. It took ages to install > Win31 on it, so it finally was returned to the vendor. But in your case it > seems a little bit different since you experience slow writes anywhere on > the medium. Would it be possible that your controller does something like > read-modify-write because of too big chunk size ? > I'm getting 10-15 meg/sec even with the largest block sizes. With dd, I set the block size to 1 megabyte, so there's no chance that the block being written is too small or that the disk block is too big. Also, it's a RAID1.