A study of radial error propagation and self-servowriting in disk drives

In this paper, the present state of the art in self servowriting of disk drives is discussed. Servowriting is a process whereby the position burst information of the track is written onto the disk by means of a apparatus known as a servowriter. Since servowriters are expensive machinery, it is desired to maximize throughput on the factory floor by minimizing the time needed for servowriting the drive. Self servowriting is a process whereby this is accomplished without a servowriter by using the servo information from a previously written track as a reference (seed) for writing the burst information on the remaining tracks. An obstacle to this process is radial error propagation, whereby the tracking errors buildup causing distortion from circularity and variable track spacing. The problem and potential solutions in this process are discussed and verified by means of simulation.