iotopiotop needs to be run as root. Once running hit ‘a’, then ‘o’ - a will display accumulated I/O instead of bandwidth, and o will only display processes or threads actually doing I/O.
I’d recommend running it as ‘sudo iotop -d0.5’, this should get it refreshing its data at a reasonable rate.
The only drawback of this mode, is that you won’t easily see results for processes which are periodically spawned and killed – you might catch them if you are continuously monitoring the output.
If you think you have processes which are periodically spawned and killed, you could try using it in batch mode: ‘sudo iotop -boat -qqq’, and pipe to grep to catch particular processes.