How Do I Find Out What’s Writing to My Drive?

When something is nagging your CPU or chugging lots of RAM, many system administrators turn to a Linux/Unix tool called “top”. But what can you use to identify a program that is doing more than its fair share of hard disk drive reading and writing? For that, you need a program called iotop.

Iotop is a free and open source program that can show you how much I/O (input/output) is going on in your system and what processes are responsible for it. The developer’s website is quick to point out that this functionality has always been a part of Linux with the “vmstat” command, but Iotop provides a familiar interface to those who like using “top” to view CPU activity and system load.

Iotop requires python, which most servers should already have, and is available in many Linux distribution software repositories. You can also download the latest version’s source code or an RPM binary from the project’s website.

To run Iotop, you need to be logged in as Root. You can then simply run the command with no options:

# iotop

It will display the processes with the highest I/O activity at the top, just like the program “top”.