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Re: Some help with dd backing up into an iso

On Tue, Mar 07, 2017 at 12:11:00AM +0000, GiaThnYgeia wrote:
> I am not very confident I am doing this right and it seems wrong,  I
> can't locate any documentation that results into proper options.
> I tried backing up an 8gb USB that has 2 partitions in it, one had 1.7gb
> of data on it.
> I used dd if=/dev/sdb of=usbfilename.iso
> The resulting image was the full size of the disk.
> To test the validity I restored reversing the order of the filenames
> if/of  but that took for ever and it was a hog on resources.  After a
> while I just gave up and killed the process.  I looked at the disk and
> it seemed complete with all files in tact, so maybe I killed it
> somewhere in the verification process.
> So I used a program called etcher which I have used with 100% success in
> the past and was surprisingly fast in burning images.
> It took for ever as well, eventually it run a verification routine and
> it was done.
> Is there someway one can avoid creating such a large iso for no reason,
> when the filesize is a fraction of the whole disk.  One way I thought of
> was to shrink the partitions to just about 99% full, and leave the blank
> part of the disk as not allocated.  Would that help?
> Is there some fancy command line that does just that?

Most of the replies seem to have assumed you didn't really want to back 
up to an ISO file system, eg to write to a CD, DVD or Blu Ray. Just in 
case that's wrong and you actually did, you'll want the growisofs 
command line tool or the brasero GUI tool.

growisofs is in a package of the same name, as is brasero.

growisofs can definitely let you choose whether to just generate the 
.iso file, or to also burn it to a disc. brasero also can I THINK, 
certainly it can burn CDs / DVDs.

In both cases the .ISO that is generated will be big enough to 
accommodate the data actually on the source disk (or SSD or USB or 
whatever) and no bigger.