Drive Imaging with dd

[Kareem Shehata]

On Fri, 2003-08-29 at 09:08, Robert Brockway wrote:
> Have you considered:
> 
> dd if=/dev/hda1 of=shuttlepod.hda1 | gzip -1

I'm not entirely sure what would happen there.  The if and of directives
tell dd to just pipe the data to the file shuttlepod.hda1, what's left
to go to gzip?

To anyone interested, I think I may have figured out the bottleneck:
2000M instructions/sec  /  20M bytes/sec = 100 instructions/byte

That's not a lot of overhead for gzip to deal with the file, especially
when you consider system overhead.  I managed to image the drive at
about 10M/s, achieving a compression rate of 75% with gzip at -5.  This
is by far the best drive imaging solution my company has seen.

> I believe you may see different performance with this.
> 
> Also, any particular reason you're using dd rather than tar?

I'm trying to take a complete snapshot of the partition so that if
*anything* happens, all I have to do is create the partition, dump the
data, and boot.  I'm not certain tar would capture everything, and NT/XP
are notorious for doing interesting things with the filesystem.

> I'm currently developing a CD which will (as one of its functions) backup
> Win* boxes (and allow easy recovery).  When I'm finished this will be
> freely redistributable.  I'll mention it on list when I'm done if anyone
> wants to download it.

I'd be interested in giving it a shot.  One more tool can only be a good
thing.

Kareem


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