The work performance of a hard disk drive (HDD) in mobile devices depends very much on its ability to withstand external disturbances. In this study, a detailed multibody structural model integrated with a complete air bearing model is developed to investigate the disk drive's response during external shocks. The head disk interface (HDI) failure mechanisms when the HDD is subjected to different shock cases are discussed. For a negative shock case in which the disk initially moves towards the head, with long pulse width, the air bearing becomes very stiff before the slider crashes on the disk, and the HDI fails only when the external load overcomes the air bearing force. For other shock cases, the slider contacts the disk due to a negative net bearing force caused by the slider-disk separation. Finally, a stiffer suspension design is proposed to improve the drive shock performance, especially during a positive shock, as under these conditions, the slider contacts the disk primarily due to the stiffness difference of the different drive components.