To find out what files a given process is using: lsof -p PID where "PID" is the process id of the process in question. As for which files are most used at

To find out what files a given process is using: lsof -p PID where "PID" is the process id of the process in question. As for which files are most used at the moment, I'm not sure. However, "iotop" will show you which processes are using the most io at the moment.