dual-stage-actuator · shipping · also dual-stage servo, DSA

Dual-stage actuator (HDD)

A dual-stage HDD actuator combines a coarse positioning stage with a fine positioning stage to control the read/write head.

Related Observatory article: Dual-stage actuator (HDD) on hesela.com

A voice-coil motor provides long-range motion while a secondary microactuator corrects finer motion near the head. Toshiba's 2011 prototype uses piezoelectric suspension elements; Seagate's 2017 SkyHawk paper documents VCM and PZT stages in a product. Two servo stages do not imply two independently addressable LBA regions or two LUNs. A multi-actuator drive may use dual-stage positioning within each assembly.

Relations

related

dual-actuator, hdd, areal-density

Limitations

• Servo bandwidth or positioning accuracy is not a direct measure of host IOPS, sequential transfer rate or field reliability. [1]

Citations

1. Sasaki and Hara, Toshiba Review 66(11), 2011: dual-stage actuator prototype, sections 2-3 (accessed 2026-10-16)
2. Seagate ImagePerfect technology paper TP694.1-1701US, January 2017, page 3: VCM/PZT dual-stage actuation (accessed 2026-10-16)
3. Chen, Prakash and Horowitz (2021), Adaptive Feedforward Reference Design for Active Vibration Rejection in Multi-Actuator Hard Disk Drives, arXiv:2110.05669v1, sections I-IV (accessed 2026-10-16)

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