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Date: Tue, 29 Sep 2009 19:30:57 +0200
From: Polytropon <freebsd@edvax.de>
To: RW <rwmaillists@googlemail.com>
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Cc: freebsd-questions@freebsd.org
Subject: Re: Disk Cloning
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On Tue, 29 Sep 2009 02:32:33 +0100, RW <rwmaillists@googlemail.com> wrote:
> On Tue, 29 Sep 2009 02:22:31 +0200
> Polytropon <freebsd@edvax.de> wrote:
> 
> > doing 1:1 copies with dd is always possible and will
> > keep content identically; remember to copy the MBR separately
> > with bs=512 and count=1 from the /dev/ad{source} device.
> 
> Why?

As far as I understood, the MBR is 512 bytes at the beginning
of the disk. If you dd the disk with a bs != 512, it won't be
transferred correctly, because in relation to the disk size you
usually do something like bs=1m. So the commands would be:

	# dd if=/dev/ad0 of=/mnt/ad0.mbr.dd bs=512 count=1
	# dd if=/dev/ad0 of=/mnt/ad0.dd bs=1m

But I have to admit that I never tried it in reality. :-)



-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...