From owner-freebsd-questions@FreeBSD.ORG Sun Sep 10 02:53:33 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org 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 0B50E16A403 for ; Sun, 10 Sep 2006 02:53:33 +0000 (UTC) (envelope-from jdow@earthlink.net) Received: from elasmtp-banded.atl.sa.earthlink.net (elasmtp-banded.atl.sa.earthlink.net [209.86.89.70]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5EBC943D49 for ; Sun, 10 Sep 2006 02:53:29 +0000 (GMT) (envelope-from jdow@earthlink.net) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=C9dOWcIEOqxoG1eL6DOxF1oN3U8vVFX/eBS3xUPKThbSDetsps41dH4BL4hzsEQn; h=Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-ELNK-Trace:X-Originating-IP; Received: from [71.116.130.69] (helo=Wednesday) by elasmtp-banded.atl.sa.earthlink.net with asmtp (Exim 4.34) id 1GMFRj-0004iS-IO for freebsd-questions@freebsd.org; Sat, 09 Sep 2006 22:53:23 -0400 Message-ID: <089801c6d484$4812a1b0$0225a8c0@Wednesday> From: "jdow" To: References: <20060909201151.30355.qmail@web32715.mail.mud.yahoo.com> Date: Sat, 9 Sep 2006 19:53:17 -0700 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-ELNK-Trace: bb89ecdb26a8f9f24d2b10475b5711209d56e1ad2b46a57527a4cb3411c1fd880c76740db0cb89d0350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 71.116.130.69 Subject: Re: Origin of hard drive parameters X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 10 Sep 2006 02:53:33 -0000 From: "stheg olloydson" > On 9 Sep 2006 14:54:09 -0000 ihilt wrote: > >>On Wednesday 06 September 2006 7:54 pm, jdow wrote: >> >>> >> Ok. Maybe the better question is: in either case, C/H/S or > LBA mode, >>> >> where are these parameters stored? >> >>> They flat out are not stored anywhere. There is a standard > algorithm >>> published by the VESA people, I believe, that provides the > data for >>> all SCSI drives and modern IDE/ATA/SATA drives. >> >>Do you know the name of this standard or where I can get it? >> >>Ian Graeme Hilt > > Actually, the stardard is created by the T13 Technical Committee And my idle curiosity would like to know why Ian is interested in such an antiquated topic? There is a size limit beyond which CHS simply does not work. The setting of CHS is in practice utterly arbitrary. For (many/most?) USB ram disk plugins the T13 standard does not apply due to internal ram layout. And so forth. (Certainly on the Amiga this CHS nonsense made no practical difference except on floppy disks or ST-506 based disk drives. And in playing with recovering a blown block zero on an Windows machine (more than once) I learned that CHS is utterly arbitrary on Windows. It is arbitrary with USB ram disk modulo the ram disk's internal layout and spares setup. And since large disks for which CHS runs out of size abound I imagine there is not a place in the 'n'x world where CHS matters. So I am suspecting historical curiosity if anything else. As for storing it - read block zero of the disk. Be DAMN careful not to WRITE to block zero. And if you DO write to block zero at about the time I quit doing such low level stuff and moved to other things there were several SCSI hard disk manufacturers using code that had a defect such that if you wrote more than one disk block starting at block 0 the whole disk was toast until you did a fresh low level format on it. One sincerely hopes THAT defect is gone these days.) {O.O} Joanne