Disk Cloning

Polytropon freebsd at edvax.de
Tue Sep 29 17:31:00 UTC 2009

On Tue, 29 Sep 2009 02:32:33 +0100, RW <rwmaillists at googlemail.com> wrote:
> On Tue, 29 Sep 2009 02:22:31 +0200
> Polytropon <freebsd at 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. :-)

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

More information about the freebsd-questions mailing list