I purchased a WD My Book 3TB from amazon 2 weeks ago. Everything work fine but… Even when not in use there is a repeated vibration every 5 seconds~ and I see this activity:
The unit reports its status to WD Drive Utilities. The unit also links to WD SmartWare and WD Backup, which can run constitutions based on your settings. If needed, you can uninstall all bundled applications in order to minimize disk activity.
While the unit is active it may vibrate if the gripping pads are sliding. If the unit has no activity and vibrates a lot then perhaps it would be best to run a diagnostic test just in case.