From owner-freebsd-questions Tue Jul 30 18:34:50 2002 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 69C3137B400 for ; Tue, 30 Jul 2002 18:34:43 -0700 (PDT) Received: from web12903.mail.yahoo.com (web12903.mail.yahoo.com [216.136.174.70]) by mx1.FreeBSD.org (Postfix) with SMTP id 7A0E843E70 for ; Tue, 30 Jul 2002 18:34:40 -0700 (PDT) (envelope-from robbakfreebsd@yahoo.co.uk) Message-ID: <20020731013439.8264.qmail@web12903.mail.yahoo.com> Received: from [203.221.121.157] by web12903.mail.yahoo.com via HTTP; Tue, 30 Jul 2002 18:34:39 PDT Date: Tue, 30 Jul 2002 18:34:39 -0700 (PDT) From: robert Backhaus Subject: Re: Can FreeBSD make a hard drive unbootable by other OS's ? To: Peter Leftwich Cc: Cherie & John Carri , FreeBSD LIST In-Reply-To: <20020730211435.A10245-100000@earl-grey.cloud9.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG --- Peter Leftwich wrote: > On Tue, 30 Jul 2002, robert Backhaus wrote: > > You can do anything with FreeBSD.... > > But you cannot undo anything (i.e. _everything_) > with FreeBSD. *wahunnn* > > > Check out references on 'Dangerously Dedicated' > disks. This looks promising - > > http://www.pl.freebsd.org/FAQ/FAQ114.html > > Slices rock. But three things aren't clear at the > above write-up: > > "The advantages of this mode are: FreeBSD owns the > entire disk, no need to > waste several fictitious `tracks' for just nothing > but a 1980-aged > simplistic partitioning model enforcing some > artificial and now rather > nonsensical constraints on how this partitioning > needs to be done. These > constraints often lead to what might be the biggest > headaches for OS > installations on PCs, geometry mismatch hassles > resulting out of two > different, redundant ways how to store the > partitioning information in the > fdisk table. See the chapter about Missing Operating > System. In > ``dangerously dedicated'' mode, the BSD bootstrap > starts at sector 0, and > this one is the only sector that always translates > into the same C/H/S > values, regardless of which `translation' your BIOS > is using for your disk. > Thus, you can also swap disks between > systems/controllers that use a > different translation scheme, without risking that > they won't boot anymore." > > It isn't clear but they seem to be "selling" the > reader on this version, > even though the misnomer and scary name has the word > dangerous in it. > > Er, that was kind of question one. Now we've got 40GB disks for the price of a good day's work, those tracks are rather unimportant. I still would use DD mode if I didn't want to dual boot, knowing that any strange formatting can be zapped away fairly easily. > > "To return a ``dangerously dedicated'' disk for > normal PC use, there are > basically two options. The first is, you write > enough NULL bytes over the > MBR to make any subsequent installation believe this > to be a blank disk. > You can do this for example with `dd if=/dev/zero > of=/dev/rsd0 count=15`" > > Here I am wondering why they say "to return a d.d.d. > for normal PC use" - > do they mean exclusively PC use? I would rest > better if it was written > from the angle of "here's why you may want to do x, > y and z oh and here is > how to -DO- x, y and z..." What this will do is, for the purposes of any fsidk/partition magic/formatter program, return the disk to a 'Unformatted, straight from the factory' state. From there, do what you want! It's the `fix all problems' shotgun solution. > > "Alternatively, the undocumented DOS ``feature'' > `fdisk /mbr` will to > install a new master boot record as well, thus > clobbering the BSD bootstrap." > > Question 3, is this fdisk /mbr a DOS command or a > FreeBSD command, or both? > Dos command. It's the dos disk partitioner. Great for this, but it's too slow for most PC installers, who use things from Ontrack that format a disk in about 5 seconds. > > It's nothing that a `ZapDisk' type utility won't > fix. > > Ooh ooh ooh! What is ZapDisk? Is it like > PartitionMagic for FreeBSDers?! > It's a dos utility that does the 'partition table obliteration' outlined above. Put it on a boot floppy and add it to your tooklit. Do a google, I couldn't find it's hompage. It'll be at tucows et al > -- > Peter Leftwich > President & Founder > Video2Video Services > Box 13692, La Jolla, CA, 92039 USA > +1-413-403-9555 > __________________________________________________ Do You Yahoo!? Yahoo! Health - Feel better, live better http://health.yahoo.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message