The present disclosure includes systems and techniques relating to control of magnetic recording devices, such as disk drives. A recording device can contain a medium that includes data tracks disposed on discrete strips of magnetic material that are arranged based on circumferences of the medium. The medium can include servo regions disposed on discrete strips of magnetic material that are arranged based on radii of the medium and extend from an inner diameter of the medium to an outer diameter of the medium. A described technique includes receiving data indicative of a waveform produced by a head operated with respect to a recording medium, detecting, when the medium is in a state of uniform magnetic polarity, a beginning of a servo region of the servo regions based on the waveform changing from a non-alternating signal to an alternating signal, the non-alternating signal being indicative of the head's path over a data track of the data tracks, and the alternating signal being indicative of the head's path over discrete magnetic strips in the servo region, performing a synchronization of one or more clocks based on the detected beginning of the servo region, and writing, based on the synchronization, data to the servo region for servo control of the medium.