DiskSpy 1.5

DiskSpy is an application that displays hard drive activity. As the developer states on the product page, Macs don't come with hard drive activity indicator lights (LEDs) anymore. In fact, one of the first things that I noticed about my first Mac was exactly that. I kept on looking for a light to see when my Mac was being slow. DiskSpy puts an icon on the menubar that blinks when your Mac reads information from your hard drive or writes it onto it.

From the application's preference window, you can adjust how frequently you want the application to look for hard drive activity. There is a sliding bar that you use to do this. The further to the left you move it, the more frequently the application will be updated. If you move it all the way to the right, the slower the updates will be. The update time is measured in microseconds. The default value is one update every 90000 microseconds. The available range is 1 every 494 microseconds to 1 every 500000 microseconds.

In my testing, with the default values, I found DiskSpy to be pretty accurate. Most of the times the activity light indicator was on, I could hear some noise from my hard drive. When you set the updates to be less frequent, the lights stay on longer.

In short, if you miss hard drive activity lights a lot, DiskSpy can be useful. However, most users won't really care much for this app.