Measure disk I/O of a running process (not one I start)

Question

I have a long-running Java server, and I'd like to measure its disk I/O activity when I tell it to perform a certain task. On Linux, is there a way to start monitoring disk I/O on a process (or a JVM, if that helps) and then stop monitoring later, and get the total bytes read and written to disk during that time period?

Answer 1

Installing and running iotop will allow you to see I/O information for individual processes: http://guichaz.free.fr/iotop/