What do you do when your computer reacts sluggishly to even the simplest commands? You probably look at its hard disk LED to determine if the disk is busy, because if it is, the only thing that really helps is waiting (apart from buying a faster disk or SSD). Problem solved – if you are sitting right next to the machine. But what if you are using a protocol like RDP or ICA to connect to a remote computer or VM? No HDD LED, no quick and simple way to check for hard drive activity. This has been bugging me enough to write a software replacement: DiskLED.

DiskLED is a little application that sits in the system tray and flickers whenever the hard disk is accessed. It looks like this:

That could be all there is to say, but I decided to make the tool a little more flexible.

Source: http://blogs.sepago.de/helge/2009/10/19/diskled-a-flexible-hard-disk-and-general-system-activity-indicator-system-tray-applet/