Write Fault Protection Against Shock Disturbance in Hard Disk Drives Without a Shock Sensor

Write fault protection performance determines the data integrity performance in hard disk drives (HDDs). It is also a critical factor in projection of new HDD products to determine the adequate servo sector number. For HDDs with a shock sensor, the write fault protection performance is rather uniform with respect to different shock disturbance. However, this is not the case when shock sensors are not available and only off-track thresholds are used to detect external shock loads. The write fault protection performance may be dependent on many factors, such as shock form and amplitude, the timing of the shock, the sampling frequency, etc. This paper studied the relationship between the write fault protection performance and shock disturbance in HDDs without shock sensors. Simulations showed that when the shock timing is random, the write fault protection performance is inversely proportional to the shock amplitude.