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Date:      Wed, 9 May 2001 19:35:37 -0500
From:      Mike Meyer <mwm@mired.org>
To:        "PC Doc" <pc-doc@worldnet.att.com>
Cc:        questions@freebsd.org
Subject:   Re: Use DD to make image copy of dual boot drive?
Message-ID:  <15097.57945.106659.703869@guru.mired.org>
In-Reply-To: <42114309@toto.iv>

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PC Doc <pc-doc@worldnet.att.com> types:
> Is copying the whole disk, sector by sector doable with DD? What would the
> command be? I think the 'c' partition refers to the whole disk so I would
> guess something like:
> 
> dd if=/dev/rwd0c of=/dev/rw1c bs=???

I used to do backups - and run them - that way. On the other hand,
that was a *long* time ago.

> I'm not sure about the devices and what would be a good block size. Do I
> need to use 512 bytes? The disks say: 32-bit mult-block-16 so that that mean
> an "efficient" block size would be 16x512? Or would a track (63x512) be
> better?

As long as it's at least 512 bytes, things should work. On the other
hand, the bigger you make it, the faster the copy will go, unless you
force your system to start swapping. I used to do half-cylinder
chunks, because a full cylinder would cause the 11/70 to start
swapping.

	<mike
--
Mike Meyer <mwm@mired.org>			http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

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