Servo layer design in dedicated servo recording system

Currently, the areal density grow in HDD still depends on the reduction of grain number per bit. In order to have less SNR penalty, it has to scale more on the track density rather than the linear density. This work proposed to insert an additional servo recording layer between data recording layer and SUL of conventional PMR media. With high quality continuous servo signals, the dedicated servo recording system has better servo performance than the conventional embedded servo for the same servo mechanics. This guarantees the high track density requirement of magnetic recording system.