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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.

Mark