The iotop command watches the I/O usage information output by the Linux kernel. It will display the current I/O usage by processes or threads on the system.
Install iotop for RHEL / CentOS Linux, use:
~# yum install iotop
Install iotop for Debian / Ubuntu Linux, use:
~# apt-get install iotop
Once installed type the following:
~# sudo iotop
To see only processes or threads actually doing I/O, instead of showing all use:
~# iotop –only
Other options for iotop command are:
Turn on non-interactive mode. Useful for logging I/O usage over time.
-n NUM, –iter=NUM
Set the number of iterations before quitting (never quit by default). This is most useful in non-interactive mode.
-d SEC, –delay=SEC
Set the delay between iterations in seconds (1 second by default). Accepts non-integer values such as 1.1 seconds.
-u USER, –user=USER
Use kilobytes instead of a human friendly unit. This mode is useful when scripting the batch mode of iotop. Instead of choosing the most appropriate unit iotop will dis‐
play all sizes in kilobytes.
Add a timestamp on each line (implies –batch). Each line will be prefixed by the current time.
suppress some lines of header (implies –batch). This option can be specified up to three times to remove header lines.
-q column names are only printed on the first iteration,
-qq column names are never printed,
-qqq the I/O summary is never printed.
Keyboard shortcuts for iotop command:
– left and right arrow keys to change sorting
– r to reverse the order
– o only to see processes or threads doing I/O
– p only shows processess
– a displays accumulated I/O instead of bandwidth, this shows I/O since iotop started
– i to change the priority of a thread or process
– q to quit