Design of a large capacity disk drive with two actuators

Large capacity disk drives, the Hitachi H-8576 and H-8598, which have two rotary actuators in the Head Disk Assembly (HAD) have been developed. The main features of these disk units are : (1) The heads, disks and rotary actuators are housed in a sealed enclosure to improve reliability and maintainability. (2) Due to the rotary actuators, lower effective mass is achieved, which permits compact design and low power consumption. Since mechanical vibration is a significant item in such drives, analysis of mechanical vibration in these units is reported in this paper.