Position-Error-Based Shock Protection in HDDs

This paper studies off-track write protection in HDDs. The system data integrity requirement is formulated based on the head/media and data track pitch configurations and a servo-mechanical system track misregistration (TMR) under various conditions. A write fault protection scheme is formulated based on position estimation through the current and predicted future PES (position error signal). The write fault trigger threshold determination and its impact on the system trade-offs are qualitatively discussed. The shock protection method applies to both conventional magnetic recording (CMR) and shingled magnetic recording (SMR).