{
  "slug": "nvme-controller-busy-time",
  "term": "NVMe Controller Busy Time",
  "aliases": [
    "Controller Busy Time",
    "controller_busy_time",
    "NVMe CBT"
  ],
  "definition": "NVMe Controller Busy Time is the cumulative number of minutes during which the controller has an outstanding I/O command, as defined by the SMART / Health Information log.",
  "note": "Base 2.3 Figure 210 places this 128-bit field at bytes 96-111. Busy time runs from an I/O Submission Queue Tail doorbell write while a command remains outstanding until its corresponding completion entry has been posted. Overlapping commands do not create additive elapsed time. [nvme-base-2-3-smart]",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "Busy-time-normalized bandwidth is not wall-clock bandwidth, and this coarse cumulative duration is not a per-command latency distribution or an average of individual latencies.",
      "citationIds": [
        "nvme-base-2-3-smart"
      ]
    }
  ],
  "related": [
    "nvme-smart-log"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "nvme-base-2-3-smart",
      "title": "NVM Express Base Specification 2.3, Figure 210, printed p. 216",
      "url": "https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-Revision-2.3-2025.08.01-Ratified.pdf",
      "accessed": "2026-10-14"
    }
  ],
  "updated": "2026-10-14"
}