What happens if you have a hanging server with next to no recognisable computation going on and with plenty of free RAM to spare? You start exploring….

Yes, this is exactly what happened recently. In addition to vmstat and iostat mentioned quite a while ago hereby I discovered iotop.

iotop is a quite nifty tool which shows you exactly which process on your machine is using up which amount of IO resources. Nice to have if you are looking for your resource hogging application. Also, some information is given about iowait, i. e. the amount of time the complete system is actually waiting for a write operation to complete. Hence, you can determine whether IO is actually a bottleneck or not.

And yea, yea, …., yea: This is a personal note 🙂