A hard disk drive electronic component processes a signal from a piezoelectric actuator to identify where on a disk the slider encounters a disk defect. The signal received from the piezoelectric actuator may be based on the mechanical propagation, through the suspension to the piezoelectric actuator, of an effect of slider contact with the protrusion. Further, an actuator may be commanded to systematically move the head slider across the writeable portion of the disk to map all the protrusions on the writeable portion of the disk.