The present invention is directed to a method and apparatus for performing seek operations in a disk drive having a disk surface with spiral servo information written thereon. The system includes first and second plugs for electrically engaging the respective receptacles. The metrology data is adjusted based on the bias information to generate bias-adjusted metrology data. The memory controller may store performance-enhancing data associated with the unit of data in the portion of the storage locations allocated to but not occupied by the first unit of data. The therapeutic agent comprises two fused 6-membered rings with at least a nitrogen at position 1 and a hydroxyl at position 8.