iotop - A Linux 'top' command for disk I/O

From this cyberciti.biz web page: “The iotop command is top like the top utility for disk I/O. It watches I/O usage information output by the Linux kernel (requires v2.6.20 or later) and displays a table of current I/O usage by processes or threads on the system. This post explains how to install and use iotop to find out what's stressing (or program names) on your hard drives under Linux operating systems.”