{
  "slug": "sata-power-disable",
  "term": "SATA Power Disable (PWDIS)",
  "aliases": [
    "PWDIS",
    "Power Disable"
  ],
  "definition": "SATA Power Disable is an optional feature using power-connector pin P3 to control power to device circuitry when supported and enabled.",
  "note": "Support, current enablement and always-enabled implementations are distinct. Power Disable and Device Sleep share P3 and are mutually exclusive. A supported feature need not be permanently active. [sata35-pwdis]\n\nFor supported devices that are not always enabled, a power-on reset disables the feature; hardware and software resets leave its enablement unchanged. Always-enabled devices retain it across resets, and a request to disable it is aborted. [sata35-pwdis]\n\nWhen enabled, PWDIS allows power with the input negated or unconnected at the host connector; disabling power and resetting the device depend on the specified signal levels and timing. [sata35-pwdis]\n\nIn documented PWDIS-equipped HDD variants, a legacy supply holding P3 at 3.3 V prevents spin-up. Check the exact drive variant and enclosure wiring: this compatibility condition does not by itself establish drive failure. [wd-pwdis]\n\nLink power management is separate: Partial and Slumber reduce PHY activity without determining whether an HDD spindle is rotating. A low-power link is not evidence that device circuitry has been power-disabled. [intel-sata-lpm]",
  "status": "shipping",
  "advantages": [
    {
      "text": "A compatible chassis can power-cycle a supporting and enabled drive without physical removal.",
      "citationIds": [
        "wd-pwdis"
      ]
    }
  ],
  "limitations": [
    {
      "text": "A mechanically fitting SATA connector does not establish PWDIS electrical compatibility.",
      "citationIds": [
        "wd-pwdis"
      ]
    }
  ],
  "related": [
    "sata",
    "hdd"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "sata35-pwdis",
      "title": "SATA-IO Serial ATA Revision 3.5 Gold (1 July 2020), sections 8.6, 13.3.12, 13.7.11.2.16 and 13.7.11.3.10",
      "url": "https://sata-io.org/system/files/specifications/SerialATA_Revision_3_5_Gold.pdf",
      "accessed": "2026-11-06"
    },
    {
      "id": "wd-pwdis",
      "title": "Western Digital: Power Disable Feature technical brief, pages 1-3 (Ultrastar product-specific evidence)",
      "url": "https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/collateral/tech-brief/tech-brief-western-digital-power-disable-pin.pdf",
      "accessed": "2026-11-06"
    },
    {
      "id": "intel-sata-lpm",
      "title": "Intel: Designing Energy Efficient SATA Devices, revision 1.63, April 2011, sections 2-2.3",
      "url": "https://www.intel.com/content/dam/doc/reference-guide/sata-devices-implementation-recommendations.pdf",
      "accessed": "2026-11-06"
    }
  ],
  "updated": "2026-11-06",
  "provenance": [
    "Specification-based explanation, not a hardware experiment. The compatibility example concerns Western Digital Ultrastar variants in the cited brief, not a current compatibility list. [wd-pwdis]"
  ]
}