From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: U160 on sym53c8xx very slow Date: Mon, 20 Oct 2003 14:32:18 +0100 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20031020133218.GK18370@parcelfarce.linux.theplanet.co.uk> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:39382 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S262570AbTJTNcT (ORCPT ); Mon, 20 Oct 2003 09:32:19 -0400 Content-Disposition: inline In-Reply-To: List-Id: linux-scsi@vger.kernel.org To: nico Cc: linux-scsi@vger.kernel.org On Mon, Oct 20, 2003 at 03:02:47PM +0200, nico wrote: > I have very poor performance with my Ultra160 disks (fujitsu MAN3184MP, > 10000rpms). > When I copy a reasonably large (500MB) file from /dev/sda2 to /dev/sda3, > it copies at a rate of 10-20 MB/sec maximum. > I was expecting better troughput. > > Here is the result of a dmesg: (Thanks for the dmesg, this is exactly what you needed to report). > sym0:6: FAST-20 WIDE SCSI 40.0 MB/s ST (50.0 ns, offset 31) Here's the problem. For some reason, your 160MB/s disc and 160MB/s controller have only managed to negotiate 40MB/s between them. You're copying from sda2 to sda3, so you should get approx half of that -- 20MB/s which fits with your report (reductions from there would be due to head seeks and so on). > Something wrong with my configuration? Is it a setting of my adapter > (Tekram DC-390-U3W) that is wrong? Should I plug it on another pci slot? > Else? I think PCI slot is very unlikely. Try a shorter SCSI cable, perhaps. BTW, looking at http://www.fujitsu.com/support/computing/storage/hdd/eol/ehdd/man3-catalog.html shows you can only expect a maximum of 40MB/s in your test: Data transfer rate To/from media 52.0 to 84.1 MB/s To/from host 160 MB/s We need to try to figure out why you only get half that though. -- "It's not Hollywood. War is real, war is primarily not about defeat or victory, it is about death. I've seen thousands and thousands of dead bodies. Do you think I want to have an academic debate on this subject?" -- Robert Fisk