Recover Fat32 files from a usb hd overwritten with a Freebsd image

[Lorenzo Salvadore]

> I'm risking to be hanged by the neck by my daughter!
> Well the fact is simple and dramatic. My daughter had a usb external hd, formatted as Fat32 filesystem, where she was keping all her jpeg photos.
> Accidentally I used this same usb drive to copy the FreeBSD-11.2-RELEASE-amd64-memstick.img using the classical
>
> sudo dd if=FreeBSD-12.0-RELEASE-amd64-memstick.img of=/dev/da0 bs=1m
>
> At the end of the process I became aware of the terrible mistake and I've never used the usb hd to start Freebsd.
> I wonder if I can try to recover the jpeg files from the 'extinct' fat32 filesystem. Surfing the net I found many solutions and I'm somewhat confused (photorec?).
>
> In order to avoid the hanging, is there anyone of you experts able to give me a useful hint for this specific case?
> Ciao
> Vittorio

If your goal is to avoid the hanging, that's easy: run,
run as fast as you can!

Now, I doubt photorec can help you, because if I understood
correctly it recovers deleted files on a filesystem that has
not been changed: this is not your case.

However, there is hope: take a look at this site:
https://www.drivesaversdatarecovery.com/
According to Wire
(see https://www.wired.com/2012/08/mat-honan-data-recovery/ ),
those guys were able to recover many photos from
an hard disk that was partially overwritten with plenty
of zeros: this is similar to your case - you overwrote
part of your device with a freebsd image.
I think (but I am unsure) that their strategy consist
in reading the part of the drive that have not been
overwritten and see what they can reconstruct following the
filesystem's rules.

You could try sending them your drive or sending it
to any organization that gives the same service (I do
not know if other organizations exist).

Lorenzo Salvadore.