I had a usb harddisk with a linux system on one partition and my media collection on another.
I deleted the linux partition, formatted this partition to fat and placed an empty file "usb" in the partition root.
Then I let raspbmc install, thinking it would install to that usb partition
Q: Can I install Raspbmc to a USB drive?
A: Yes — but the SD card will still be needed to boot. This may seem futile then, however, the performance gains are admirable. This can be done easily through the Windows installer. For users installing via Python or manually, all that is needed is to create a file called ‘usb’ on the fat32 partition. The installer will then install to the first detected USB drive.
Instead it wiped the whole disk and installed itself there. All my media gone for now.
What would you advise me to do next?
How can I recover as much as possible?
There are thousands of files lost. How do I find out, which files where damaged (truncaded, partially overwritten, etc...) other than by trial and error, once recovered.