log file for files being copied to USB
Yes )) monitoring the files is the best thing to control them .
I am using that soft to “control” them : USB Detect .
http://usbdetect.com/
It will help protect your files on your computer and network.
It does this by monitoring all USB drive activity.
When someone plugs any type of USB drive into the computer, the software recognizes this and will add the activity to a log.
It saves the date/time and the username logged into the computer.
When a user copies files to the USB drive, all file activity will be logged also.
))
Very nice soft ,many option and email notifications etc ,,, . You can try it by installing the demo version .
Good luck ,