absolute vs. relative offsets in disklabel

Dan Nelson dnelson at allantgroup.com
Mon Jul 31 20:50:45 UTC 2006

In the last episode (Aug 01), Dmitry Marakasov said:
> Recent `disklabel differences FreeBSD, DragonFly' thread gave me a
> thought - why do we have absolute offsets in disklabel? AFAIK, on
> NetBSD and OpenBSD, label is not necessarily located `near'
> filesystems stored in it's partitions - and even disklabel utility
> shows absolute offsets (with 'c' covering entire device). FreeBSD,
> however, seem to step far away from that standart - 8 partitions
> instead of 16, label located in the beginning of a partition,
> bsdlabel shows relative offsets. Now I wonder if there are any
> reasons for offsets to be actually absolute? There are many weighty
> arguments for relative offsets:

I asked this question a few years ago after having problems dd'ing a
FreeBSD installation from one disk to another, and the answer was "it's
always been that way" :) It shouldn't be too hard to have the code
autodetect whether the offsets are relative or absolute by looking at
what the 'c' partition's offset is.

	Dan Nelson
	dnelson at allantgroup.com

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