Monitor disk read/write IO per second on Debian

Question

I'm trying to monitor disk I/Os on a server.
I need to fetch two metrics:

• read IO/sec
• write IO/sec

Using iotop I'm able to read those metrics (DISK READ and DISK WRITE). My major problem is that I can't use any non-built-in commands.

How can I get an instant snapshot of read IO/sec and write IO/sec without any third-party utility?

Answer 1

Look in file /proc/diskstats it has the info you need. read http://www.kernel.org/doc/Documentation/iostats.txt

The files in /proc are not real files, they are dynamic pseudo files.

Also, if it does not depend on any non existent dynamic libraries you can copy pstop to ~/bin then chmod +x ~/bin/pstop. If it does you will have to compile a staticly linked version.

Answer 2

I finally found a good way to read the I/O metrics:

1. Get all processes ID from /proc/ by listing the directory
2. Extract the metrics from cat /proc/[pid]/io
3. Do some maths