{
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-12",
  "slug": "command-based-switching",
  "term": "Command-based switching (SATA)",
  "aliases": [
    "SATA CBS"
  ],
  "definition": "Command-based switching restricts outstanding commands behind a SATA port multiplier to one downstream device at a time.",
  "note": "The host completes work for the selected device before issuing commands to another target. This restriction concerns the target, not a universal one-command queue. [sata-switching]\n\nAHCI explicitly permits NCQ operation in this mode, with the active queue drained before changing targets. [ahci-switching]\n\nA busy target can delay access to other attached drives even while those drives could perform work independently. [switching-context]",
  "related": [
    "sata-port-multiplier",
    "fis-based-switching",
    "native-command-queuing",
    "ahci"
  ],
  "citations": [
    {
      "id": "sata-switching",
      "title": "SATA-IO Serial ATA Revision 2.6, section 16.7, page 545: command-based and FIS-based switching",
      "url": "https://sata-io.org/system/files/specifications/SerialATA_Revision_2_6_Gold.pdf",
      "accessed": "2026-10-19"
    },
    {
      "id": "ahci-switching",
      "title": "Intel AHCI 1.3.1, sections 3.1.1, 3.3.7, 3.3.16 and 9: capabilities and port-multiplier operation",
      "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"
    },
    {
      "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"
    }
  ],
  "provenance": [
    "SATA-IO sections were checked through indexed primary-specification text; direct PDF retrieval was unavailable. [sata-switching]"
  ]
}