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Date:      Tue, 4 Sep 2001 01:30:24 -0500
From:      Mike Meyer <mwm@mired.org>
To:        "Pietralla, Siegfried P" <siegfried.pietralla@eds.com>
Cc:        questions@freebsd.org
Subject:   Re: can't dd blocksize=446
Message-ID:  <15252.29952.597012.181719@guru.mired.org>
In-Reply-To: <15435133@toto.iv>

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Pietralla, Siegfried P <siegfried.pietralla@eds.com> types:
> hi all,
> i installed 4.3 recently after running 2.2.6 for ages - but now i've got a
> >8Gb hd :) and i wanted to make use of it. in the past when i've copied my
> installation to a second hd for backup i've been able to copy the bootloader
> (?) from one to another with 'dd if=/dev/ad0 of=/dev/ad1 bs=446 count=1' but
> now dd reports ( i think ) "invalid argument" - it only allows bs=512. is
> this some sort of clean up of dd to make it work to spec? 

Actually, it's a clean up of the disk devices. Raw devices have always
behaved that way. Cooked devices sometimes behaved that way, but it
wasn't reliable. They're now gone.

> how do i get the behaviour i'm after?

Just use 512 bytes. If you really want to copy 446 bytes without
overwriting the last bit, you'll need to create the sector by hand
before copying it to the disk.

> or what is the proper way to just install the normal
> freebsd type bootloader ( the F1,F2,F3,F4,F5 one). i tried 'fdisk -B' but
> booting came up with "missing operating system".

That sounds like you're not issuing the correct "fdisk -B" command, as
that's the proper way to install the standalone bootloader. To get the
boot loader you want, you need to use boot0cfg. See the man page for
details.

> i guess i could just try
> dd'ing the 512 bytes and then fdisk to put the pn table back - would that
> work? however i'd still like to be able to separately backup my bootloader
> and partition map into different files. any thoughts and directions are
> welcome.

The slice and partition tables have very little information on them,
and don't change very often. I tend to print copies - after all, it's
usually just one page per disk - and store those with the backups. The
source for the bootloader are in the tree, and on the distribution
CDROM, and available over the net if worst comes to worst - so I don't
bother backing it up.

	<mike
--
Mike Meyer <mwm@mired.org>			http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

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