The second edition of this monograph provides a systematic treatment of the design of hard disk drive servo systems updated to reflect recent improvements in spindle speed and bit density and other changes in this fast-moving field. In particular, it focuses on the applications of some newly developed results in control theory, i.e., robust and perfect tracking control and composite non-linear feedback control which are suitable for track following and seeking respectively. Emphasis is placed on hard disk drive servo systems with single- or dual-stage actuation using a voice-coil-motor actuator enhanced in the latter case by the addition of a micro-actuator providing faster responses and therefore higher bandwidth in track following. Modeling and compensation of nonlinearities and friction in microdrives, disturbance rejection and resonance compensation are also addressed. The Linear Systems and CNF MATLAB® toolkits used to develop many of the results can be downloaded from the book's website.