Systems and methods are disclosed for phase locking of a clock. In some embodiments, a phase locked clock (PLC) module can phase-lock a write clock to a media written with multiple servo zones of different frequencies. In some implementations, this can be utilized to perform a self-servo write (SSW) of a disc surface within a hard disc drive (HDD). A PLC module can perform a method of writing with a single frequency phase coherently while a read element passes over servo zones with different frequencies. While the PLC module can perform such methods for a SSW process, the methods can also be utilized for other applications that can benefit from writing with a single frequency phase coherently based on servo zones with different frequencies.

At least a portion of a first servo mark is read using a first read head during a rotation of a disk, the rotation comprising no more than 360 degrees. At least a portion of a second servo mark is read using a second read head during the rotation of the disk. Tracking positions of the first read head and the second read head are determined during the rotation based on reading the first servo mark and the second servo mark.

Systems and methods are disclosed for phase locking of a clock. In some embodiments, a phase locked clock (PLC) module can phase-lock a write clock to a media written with multiple servo zones of different frequencies. In some implementations, this can be utilized to perform a self-servo write (SSW) of a disc surface within a hard disc drive (HDD). A PLC module can perform a method of writing with a single frequency phase coherently while a read element passes over servo zones with different frequencies. While the PLC module can perform such methods for a SSW process, the methods can also be utilized for other applications that can benefit from writing with a single frequency phase coherently based on servo zones with different frequencies.

This disclosure describes apparatuses and techniques for multi-channel servo demodulation. Multiple servo demodulation channels enable additional information to be obtained during the self-servo writing process, such as relative positions of multiple read heads and tracking of multiple servo patterns. This additional information enhances accuracy for self-servo writing and can lead to higher recording densities in media drives, and thus more storage with little or no additional cost.

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo tracks and a plurality of data tracks defined by the servo tracks. Each servo track is defined by a first set of servo sectors interleaved with a second set of servo sectors, wherein each servo sector comprises a servo burst field. The servo burst field of the first set of servo sectors has a first length and the servo burst field of the second set of servo sectors has a second length longer than the first length. Data is written to a first data track by reading at least one of the second set of servo sectors and skipping the read of at least part of one of the first set of servo sectors, and servoing the head over the first data track in response to reading the second set servo sector.

According to embodiments of the present invention, a method of writing servo information on a storage medium is provided. The method includes applying heat to a servo portion of a storage medium, and applying a magnetic field to the servo portion that is heated to write servo information on the servo portion. According to further embodiments of the present invention, an arrangement for writing servo information on a storage medium and a method of forming a storage medium are also provided.