backup drive bootabel

Matthew Seaman m.seaman at
Wed Nov 26 07:29:02 PST 2003

On Wed, Nov 26, 2003 at 06:39:42AM -0800, Noah wrote:

> I am using FreeBSD 4.8 Stable
> # boot0cfg -B -b /boot/mbr -s 1 da1
> boot0cfg: /boot/mbr: unknown or incompatible boot code
> # ls -l /boot/mbr
> -r--r--r--  1 root  wheel  512 Aug 24 14:26 /boot/mbr
> so I am not clear what the issue is here?

Opps. Sorry.  boot0cfg only operates on /boot/boot0 which is the
FreeBSD special Master Boot Record: part of the boot0, boot1, boot2

To deal with a standard MBR, you have to use fdisk(8).  Try:

    # fdisk -B -b /boot/mbr -i da1

This will walk you through the current settings interactively, letting
you generate a slice table, change the active slice and rewrite the
boot code.

Of course, just to confuse you, fdisk(8) will talk all about
"partitions", but be assured it actually means "slices" in *BSD speak.
(partitions are generated within each slice using disklabel(8) which
is a BSD specific thing.  slices are generic for practically all OSes
that can run on the IA32 architecture from DOS onwards.)

> the disk is a little bit of  a different size with different partition sizes.
>  woudl that Make a difference.  what esle can I check here?

The disk geometry won't make any difference to the boot block.
fdisk(8) will read in the current partition table and give you the
opportunity to modify things, but don't do that unless you really do
intend to wipe the disk contents.



Dr Matthew J Seaman MA, D.Phil.                       26 The Paddocks
                                                      Savill Way
PGP:         Marlow
Tel: +44 1628 476614                                  Bucks., SL7 1TH UK
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