Check increasing load on hard disks with iotop command

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
OR
~# iotop

To see only processes or threads actually doing I/O, instead of showing all use:

~# iotop –only

Other options for iotop command are:

-b, –batch
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
-k, –kilobytes
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.
-t, –time
Add a timestamp on each line (implies –batch). Each line will be prefixed by the current time.
-q, –quiet
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

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