Apple :: Loud HD Click Sound When Picking Up Laptop While On

When the laptop is on and I pick it up to move it I would often hear a loud CLICK sound coming from the HD. It had me freaked out that something was loose or that the heads were scratching the platters.

I just came across an article explaining what this noise has been. It is the sound of the read/write heads parking because of the "Sudden Motion Sensor" built into the laptop. It senses the rapid movement when I pick up the laptop and then it parks the heads to prevent scratching the platters... that is the click sound of the heads parking.

The sensor is a tri-axis accelerometer that detects sudden changes in "position and accelerated movement".

Anyways, I tested this to see if it was the "sudden motion sensor" parking the heads:
- first I confirmed that the sound would still occur when picking up the laptop and tilting it quickly while still on
- then I checked the sensor's settings to see if it was really on by running a command I found in the linked article.
- then I turned off the sensor (that command is also in the article).
- then I tested by picking up the laptop again and tilting it quickly...

no more CLICK

I enabled the sensor again because it is better to have it enabled than to risk scratching a platter if I drop the laptop. I'm just happy to have found the source of the CLICK and to know it wasn't a faulty HDD.

Here is the article:

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