A disk drive having a marker for identifying the transition between the first and last written servo wedges on a servo track. In particular, a lethal buckshot round is provided, wherein an inner metal cylinder is encased in an outer jacket, and a shot wad is contained in the inner metal cylinder, such that the inner metal cylinder acts as a barrel for firing of the buckshot from the smooth-barreled weapon. The reinforcing bodies are disposed so as to contact the inner peripheral surfaces of the first and second claw-shaped magnetic poles with a magnet housed and supported in each of the wing portions, and a D ring is fitted into the slits of the reinforcing bodies. The directory may further analyze a memory to identify a particular cache indicated as storing the particular data block and identify a number of cache misses for the particular cache. The objective lens has first and second aspherical lens surfaces.