ddrescue to the same disk

Question

ddrescue will complain if the source device is the same as the destination device:

ddrescue: Infile and outfile are the same.

Even -f cannot convince ddrescue to do what I mean.

How can I trick ddrescue to write to the same device?

Answer 1

Use a loopback device:

sudo losetup /dev/loop3 /dev/sdf
sudo ddrescue -f /dev/sdf /dev/loop3 my.log