{
  "slug": "dual-stage-actuator",
  "term": "Dual-stage actuator (HDD)",
  "aliases": [
    "dual-stage servo",
    "DSA"
  ],
  "definition": "A dual-stage HDD actuator combines a coarse positioning stage with a fine positioning stage to control the read/write head.",
  "note": "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.",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "Servo bandwidth or positioning accuracy is not a direct measure of host IOPS, sequential transfer rate or field reliability.",
      "citationIds": [
        "dual-stage-toshiba"
      ]
    }
  ],
  "related": [
    "dual-actuator",
    "hdd",
    "areal-density"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "dual-stage-toshiba",
      "title": "Sasaki and Hara, Toshiba Review 66(11), 2011: dual-stage actuator prototype, sections 2-3",
      "url": "https://toshiba.semicon-storage.com/content/dam/toshiba-ss-v3/master/en/storage/technology-center/ToshibaReview_vol66n11.pdf",
      "accessed": "2026-10-16"
    },
    {
      "id": "seagate-skyhawk",
      "title": "Seagate ImagePerfect technology paper TP694.1-1701US, January 2017, page 3: VCM/PZT dual-stage actuation",
      "url": "https://www.seagate.com/files/www-content/product-content/skyhawk/files/image-perfect-smart-safe-solution-cb4-tp694-1-1701us.pdf",
      "accessed": "2026-10-16"
    },
    {
      "id": "dual-coupling-chen",
      "title": "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",
      "url": "https://arxiv.org/abs/2110.05669v1",
      "accessed": "2026-10-16"
    }
  ],
  "updated": "2026-10-16"
}