[ale] File “ropes”

[Greg Freemyer]

I googled "mount segmented dd image" and this was the first hit.

http://davnads.blogspot.com/2009/11/linux-mount-split-dd-file-images.html

I think there are other ways, but the key is to use multiple losetup
commands to access your segments.

Good Luck
Greg

On Wed, Oct 6, 2010 at 10:43 AM, Michael B. Trausch <mike at trausch.us> wrote:

> Hey everyone,
>
> I have an interesting little problem.
>
> I was doing a backup of someone's hard disk drive in their laptop
> computer, and the first time I ran dd it failed (albeit on an even block
> boundary).  So I ran the dd command again, skipping all the sectors that
> were already copied, and put that in a second file.
>
> Now, I have two very large files that have the HDD image in them.  What
> I want to do is combine them into one file.  I want to do this
> efficiently, though; the normal "cat hdd-* > hdd-full.img" method will
> take hours and hours, and I don't want that.
>
> I'm using btrfs, and I thought that maybe there would be some way that I
> could create a file that would have two extents, mapping to the first
> image and second image, so that I can mount the image loopback and begin
> extracting files.  But I can not find a way to do that --- The way that
> I'd expect it to be done in btrfs would be to treat the files as
> “ropes” (á la strings) and be able to efficiently and logically put the
> ropes together.  I seem to be barking up the wrong tree there, though.
>
> Is there something out there that would permit me to solve this problem
> in an efficient way without actually cat'ing the files together?  I
> don't want to double the disk space used by this even temporarily since
> that would put me, well, pretty much over-full.  :-)  I could write a
> program that created a large sparse file and filled the sparse file
> block-by-block, effectively moving chunks from one file to the other,
> but that, too, would take hours to do and if the power went out, I'd be
> in a pretty un-happy state.
>
>        --- Mike
>
> _______________________________________________
> Ale mailing list
> Ale at ale.org
> http://mail.ale.org/mailman/listinfo/ale
> See JOBS, ANNOUNCE and SCHOOLS lists at
> http://mail.ale.org/mailman/listinfo
>



-- 
Greg Freemyer
Head of EDD Tape Extraction and Processing team
Litigation Triage Solutions Specialist
http://www.linkedin.com/in/gregfreemyer
CNN/TruTV Aired Forensic Imaging Demo -

http://insession.blogs.cnn.com/2010/03/23/how-computer-evidence-gets-retrieved/

The Norcross Group
The Intersection of Evidence & Technology
http://www.norcrossgroup.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.ale.org/pipermail/ale/attachments/20101006/c935e9e9/attachment.html