{
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-12",
  "slug": "sata-port-multiplier",
  "term": "SATA port multiplier",
  "aliases": [
    "SATA PM",
    "SATA PMP"
  ],
  "definition": "A SATA port multiplier connects several downstream SATA devices to one host SATA port.",
  "note": "Device ports use addresses 0 through 14; address 15 is the control port, not a sixteenth disk. Cascaded multipliers are not supported. [sata-35]\n\nThe devices share the upstream link. Adding drives expands attachment capacity, not the host port's bandwidth. Host support and the switching method matter when several drives are busy. [switching-context]\n\nA COMRESET issued to the host port resets every attached device. Separate downstream disks therefore do not imply independent reset scope. [ahci-recovery]",
  "related": [
    "sata",
    "ahci",
    "sata-fis",
    "command-based-switching",
    "fis-based-switching"
  ],
  "citations": [
    {
      "id": "sata-35",
      "title": "SATA-IO Serial ATA Revision 3.5, sections 10.4-10.5 and 16.1-16.3: FIS and port multipliers",
      "url": "https://sata-io.org/system/files/specifications/SerialATA_Revision_3_5_Gold.pdf",
      "accessed": "2026-10-19"
    },
    {
      "id": "switching-context",
      "title": "Scott Knowlton, Synopsys: Understanding SATA FIS-Based Switching (2013), connectivity and shared bandwidth",
      "url": "https://www.chipestimate.com/Understanding-SATA-FIS-Based-Switching/Synopsys/Technical-Article/2013/01/22",
      "accessed": "2026-10-19"
    },
    {
      "id": "ahci-recovery",
      "title": "Intel AHCI 1.3.1, sections 9.3.6.1-9.3.6.2 and 9.3.8: device-specific recovery and host-port reset",
      "url": "https://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/serial-ata-ahci-spec-rev1-3-1.pdf",
      "accessed": "2026-10-19"
    }
  ],
  "provenance": [
    "SATA-IO sections were checked through indexed primary-specification text; direct PDF retrieval was unavailable. [sata-35]"
  ]
}