How to monitor disk activity on your Mac's Dock

Con Activity Monitor, it's easy to monitor your Mac's disk activity at a glance directly from the Dock. A special option replaces the normal Activity Monitor icon with a small animated graph showing disk usage over time in your Dock. Here's how to set it up.

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First, abra “Activity monitor”. One of the easiest ways to do this is through Spotlight. Click the icon of the “forget” in the menu bar, or press Command + Space.

When a search bar appears, scribe “activity monitor” and press “Return”.

Next, right-click on the Activity Monitor Dock icon and a small menu will appear. On the menu, select “Docking icon”, then select “Show disk activity”.

Once activated “Show disk activity”, the Activity Monitor Dock icon will turn into a small animated graph showing disk activity readings over time, moving slowly from right to left.

(By default, the graph is updated every 5 seconds. To change the update rate, select View> Refresh rate in the menu bar at the top of the screen).

By default, the graph shows “readings per second” in blue and “scriptures per second” in red. Both are raw counts of the number of reads and writes to disk per second. This is commonly called “I”, which is the abbreviation of “entry / Exit”.

Instead, it is feasible to change the dock chart so that the chart bytes are read and written. To do it, look at the main window of Activity Monitor. (If it's not open, press Command + 1 in order to show up).

Click on the tab “Disco”, then look at the bottom of the window. Right above the little graph in the window, click on the header that says “I” and change it to “Data”.

Once selected “Data”, Dock chart changes instantly. Now, the blue line represents bytes of data read per second and the red line represents bytes of data written per second.

When you have configured the Disk Activity Dock icon as desired, you can close the main window of Activity Monitor. The app will keep running in the background while you perform other tasks.

Even with the main window closed, the disk activity graph in the Dock will continue to update over time. But Activity Monitor must remain open. If you close it, your Dock icon will return to normal.

Later, if you want to go back to the normal Activity Monitor icon while it is still running, right click on the Activity Monitor Dock icon again and select the Dock icon> Show the app icon. Have fun!