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Date:      Wed, 30 Sep 2009 11:30:58 -0400
From:      Jerry McAllister <jerrymc@msu.edu>
To:        Polytropon <freebsd@edvax.de>
Cc:        PJ <af.gourmet@videotron.ca>, freebsd-questions@freebsd.org
Subject:   Re: backups & cloning
Message-ID:  <20090930153058.GC27266@gizmo.acns.msu.edu>
In-Reply-To: <20090930050805.7f9d7252.freebsd@edvax.de>
References:  <4AC29BE6.4000505@videotron.ca> <20090930023051.cff2b0b4.freebsd@edvax.de> <4AC2C104.7090206@videotron.ca> <20090930050805.7f9d7252.freebsd@edvax.de>

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On Wed, Sep 30, 2009 at 05:08:05AM +0200, Polytropon wrote:

> Forgot to mention this:
> 
> 
> On Tue, 29 Sep 2009 22:23:00 -0400, PJ <af.gourmet@videotron.ca> wrote:
> > 1. will the s1a slice dump the entire system, that is, the a, d, e, f
> > and g slices or is it partitions?
> 
> The ad0s1 slice (containing the a, d, e, f and g partitions) can
> be copied 1:1 with dd. By using dump + restore, the partitions
> need to be copied after another. In each case, the entire system
> will be copied. For this purpose, even the long lasting
> 
> 	# dd if=/dev/ad0 of=/dev/da0 bs=1m
> 	# dd if=/dev/ad0 of=/dev/da0 bs=512 count=1
> 
> method can be used.
> 

It can be used, but it is not a good way to do it.
That is because it copies sector by sector and the new 
disk/filesystem may not match the old exactly.  Besides
when it is newly written on a file by file basis, it can
be more efficiently laid out and accomodate any changes in
size and sector addressing.  dd cannot do that.

////jerry


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