A "magical" HDD formatting question.

[Sthu Deus <sthu.deus@gmail.com>]

Good day.


Is there a way to:

. boot from internal HDD then

. chroot or whatever to externel HDD (with the same Debian clone
copy)

. format the internal HDD,

. move the OS back from external to internal HDD?

I have to do so because it is impossible for now to boot from CD/USB.
And I want to move from ext3 to ext4.


Thank You for Your time.