backups & cloning

Jerry McAllister jerrymc at
Wed Sep 30 15:31:04 UTC 2009

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 at> 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.


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