Disk imaging program?

John Hupp ubuntu at prpcompany.com
Wed Jun 25 13:26:18 UTC 2014

On 6/25/2014 4:41 AM, Nils Kassube wrote:
> 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.
> Nils

Nils & Niles,

Sorry, let me clarify: when I asked if dd knows how to prompt for the 
next split, I meant during a restore operation, if one has split an 
image and burned it onto several DVD's.

And when I said "boot sector," maybe I should have said MBR? Something 
that preserves the bootloader and partition table. (Clonezilla preserves 
those, and does not, at least in general, use dd.  But of course it 
doesn't know how to span DVD's for the imaging and restoring.)

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