Disk imaging program?

Nils Kassube kassube at gmx.net
Wed Jun 25 08:41:08 UTC 2014

John Hupp wrote:
> On 6/24/2014 4:05 PM, Niles Rogoff wrote:
> > _x_ imaging of Windows and Linux partitions in a single
> > image-the-disk operation that includes the boot sector and related
> > structures _x*_ bootable disc can do offline image backup and
> > restore
> > _x**_ image to spanned DVD's
> > _x***_ good compression
> > _x_ free for business as well as personal use
> > 
> > dd
> > 
> > * ubuntu, slitaz or any other livecd
> > ** step 1: http://www.computerhope.com/unix/usplit.htm Step 2:
> > /dev/cdrom *** tar -czf
> Interesting idea.  Though dd does a slow and heavy sector-by-sector
> copy, if speed is not an issue, then you address the compression angle
> with tar.  But I wonder if dd copies currently unallocated sectors
> with old data in them, and if tar is then constrained to preserve
> that data in its compression?  If so, then you're compressing data
> you don't even want.  (I suppose I could begin the whole thing by
> wiping the free space, but I wouldn't add that step unless it turned
> out that I need to.)

You asked for an application that preserves the boot sector, so you 
obviously want something that does sector by sector copy. Therefore dd 
seems to be a sensible choice to me. If you want to keep data only, I 
would suggest to use tar, but then the boot sector is gone.

Furthermore there seems to be a little confusion of what tar does. It is 
not a compression tool but an archive program which doesn't do 
compression on its own. The suggested command "tar -czf" would invoke 
gzip for compression but it wouldn't be useful together with dd IMHO 
because using gzip alone would suffice.

> And can you kindly confirm that dd knows how to prompt for the next
> split?

No, I don't think dd can prompt for a split. But I think tar could do 
that - have a look at the -F and -M options.


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