A storage device includes a probe having plural tips, and a storage medium having a surface. At least a first one of the tips is adapted to form a dent in the storage medium, and at least a second one of the tips is adapted to be electrically contact the surface of the storage medium in response to the first tip being engaged in the dent. The second tip is electrically isolated from the storage medium in response to the first tip being engaged on the surface of the storage medium and not being engaged in the dent.