iotop - 0.6-24-g733f3f8-1.1 main

iotop does for I/O usage what top(1) does for CPU usage. It watches I/O
usage information output by the Linux kernel and displays a table of
current I/O usage by processes on the system. It is handy for answering
the question "Why is the disk churning so much?".
.
iotop can only run under a Linux 2.6.20 or later kernel built with the
CONFIG_TASKSTATS, CONFIG_TASK_DELAY_ACCT, CONFIG_TASK_IO_ACCOUNTING and
CONFIG_VM_EVENT_COUNTERS build config options on.