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Date:      Mon, 31 Jul 2006 15:50:44 -0500
From:      Dan Nelson <dnelson@allantgroup.com>
To:        freebsd-hackers@freebsd.org
Subject:   Re: absolute vs. relative offsets in disklabel
Message-ID:  <20060731205043.GD63872@dan.emsphone.com>
In-Reply-To: <20060731203213.GA75233@hades.panopticon>
References:  <20060731203213.GA75233@hades.panopticon>

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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@allantgroup.com



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