DX can be used to move files that haven't been edited or accessed in a given period of time to some other media. Once those files are moved you can run a file report which will list every file that's moved; essentially every file that hasn't been edited or accessed in that given period of time. You can set up rules to move only specific file types such as MP3s, etc. I would recommend reading through a DX manual (available through Powerlink) to get a much better grasp on its capabilities.