From owner-freebsd-hackers  Wed Feb  5 22:22:24 1997
Return-Path: <owner-hackers>
Received: (from root@localhost)
          by freefall.freebsd.org (8.8.5/8.8.5) id WAA21742
          for hackers-outgoing; Wed, 5 Feb 1997 22:22:24 -0800 (PST)
Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.19])
          by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id WAA21688
          for <hackers@freebsd.org>; Wed, 5 Feb 1997 22:22:18 -0800 (PST)
Received: (from bde@localhost) by godzilla.zeta.org.au (8.8.3/8.6.9) id RAA09563; Thu, 6 Feb 1997 17:16:25 +1100
Date: Thu, 6 Feb 1997 17:16:25 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199702060616.RAA09563@godzilla.zeta.org.au>
To: durham@w2xo.pgh.pa.us, hackers@freebsd.org
Subject: Re: DOS partition trouble
Sender: owner-hackers@freebsd.org
X-Loop: FreeBSD.org
Precedence: bulk

>Twice now, I have removed a DOS partition
>from a disk with both DOS and FreeBSD
>partitions and been unable to boot FreeBSD.
>...
>I had tried running the partition editor when I had no DOS
>partition and it gave all indications of sucessfully writing
>out the boot block, but would not boot until I remade the
>DOS partition. Trying to mount the root directory from the MFS
>on the boot floppy gave a "bad super block" error.

For SCSI disks with at least ncr controllers, this could be caused
a DOS partition that ends on a cylinder boundary and FreeBSD partition
that doesn't.  When you remove the DOS partition, the controller's BIOS
will have problems determining the disk geometry.

Bruce