Linux Administration Cookbook

iotop

Invoked with the following command, iotop displays I/O usage on a system, by process:

$ sudo iotop

On our system, this means that we can see very little in the way of activity (because the VM isn't doing much by default):

As with ps, the square brackets around a thread (such as "[kthrotld]", for example) denote kernel threads. 

If we wanted to see I/O in action, we could do the following in another session:

$ fallocate -l 2G examplefile$ rsync -z -P --bwlimit=2M examplefile examplefile-copied

We're specifically compressing and bandwidth, limiting the transfer of the preceding file. We've also got a -P in there, but that's mostly so that ...