For reference I want to start work on the next iteration of this plugin in 1-2 months (I'd like this functionality too), its behind a few other projects atm, and the next iteration will mean porting to a different drawing library resulting in an unknown amount of time wastage.

I have this functionality completed locally (monitoring the various stats from /proc/diskstats and reporting on the change per second, or the raw value if that doesn't make sense), and I have implemented a generic monitor (where you can just dump a number into a file and then plot it in a visualisation).

If you're interested in testing, I can push the branch to the XFCE repo and you can check it out.

Otherwise I'm planning to release in ~1 week.

I'll give it a test, sure.

Cheers - see the new branch: http://git.xfce.org/panel-plugins/xfce4-hardware-monitor-plugin/log/?h=omegaphil/graph-disk-io

Note that the build requirements have changed a little - libglade has been removed, libgtkmm to v2.24.

Currently theres no new documentation, I plan to do that on Friday+ - basically see on the Storage tab, the new Disk Statistics option - you select your disk then your stat. Note that for source stats that are essentially permanently increasing numbers, the actual stat reported in the visualisation is the 'change per second' (otherwise you'd just get a juddering rising line).

There is also a new Generic Monitor (see the last tab), that allows you to visualise pretty much any source data number (however as the graph space is so small, large number + small change won't make a lot of visible difference) read from a file, if you're interested.

Implemented in v1.5.