From owner-freebsd-questions@FreeBSD.ORG Fri Feb 13 13:41:09 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 91F4316A4CE for ; Fri, 13 Feb 2004 13:41:09 -0800 (PST) Received: from mail3.speakeasy.net (mail3.speakeasy.net [216.254.0.203]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7ABCD43D2F for ; Fri, 13 Feb 2004 13:41:09 -0800 (PST) (envelope-from jdarnold@buddydog.org) Received: (qmail 5135 invoked from network); 13 Feb 2004 21:41:09 -0000 Received: from dsl092-076-225.bos1.dsl.speakeasy.net (HELO buddydog.org) ([66.92.76.225]) (envelope-sender ) by mail3.speakeasy.net (qmail-ldap-1.03) with SMTP for ; 13 Feb 2004 21:41:09 -0000 Message-ID: <402D4474.3060009@buddydog.org> Date: Fri, 13 Feb 2004 16:41:08 -0500 From: Jonathan Arnold User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7a) Gecko/20040119 MultiZilla/1.6.0.0e X-Accept-Language: en-us, en, ja MIME-Version: 1.0 To: freebsd-questions@FreeBSD.ORG References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: Why would drive run at UDMA33? (Segate 80GB) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 13 Feb 2004 21:41:09 -0000 JJB wrote: >> This is not true. With today's computers, all disks will operate at >> their highest speed, not matter what other device they are paired >> with. >> Their transfer rate may be slowed down if *both* devices are >> accessed at >> the exact same time, but that's nothing to worry about generally. So >> just >> because you have a CD-ROM and an UDMA100 disk on the same channel, >> it doesn't mean the UDMA100 disk will be slowed in nearly any >> noticable >> fashion. > I have an PC with mfg date of 5/2003 and the motherboard manually > has warning note about separating the cdrom drive to the secondary > IDE controller because it will force the IDE controller to step down > the max speed to the slowest device. This was not only for cdrom > drives but also mixing UDMA100 and UDMA66 and UDMA33 disk on any IDE > controller. IDE max controller speed is set by bios at boot time > after the probe post process completes. So just exactly what time > period are you referencing by "With today's computers"? DO you work > for Bios chip manufacture, or write the FBSD bios's boot probe code? > What is your technical background to make such an authoritative > statement in light of so much information to the contrary? All you need to do is to Google for "hard drive cd-rom myth" and you'll get plenty of places that explain this. I guarantee you that a UDMA100 drive won't be set at PIO4 just because there's a CD-ROM drive on the same channel. Your manual is probably talking about exactly what I said - if both devices are accessed at the same time, the transfer will occur at the slower rate. But that does not mean either the bios or FreeBSD doesn't know that a UDMA100 drive is out there. In fact, my FreeBSD has both a UDMA66 and 100 on it, and FreeBSD knows all about the two. And if you are just getting stuff from the hard drive (which is probably 95+% of the time), then you have a perfectly functioning UDMA100 drive. > second device to the ribbon. Now if the devices are jumper as master > and slave it does make an difference which of the 2 closely spaced > nipples are used as the nipples have default meanings. And I believe I don't think this is true either. I've hooked up a lot of drives in my time, and I've never seen this. And no "build it yourself" guide that I was able to find on the 'net mentioned anything at all about which nipple to plug into the slave or master drive. -- Jonathan Arnold (mailto:jdarnold@buddydog.org) Daemon Dancing in the Dark, a FreeBSD weblog: http://freebsd.amazingdev.com/blog/