{
  "slug": "nvme-critical-composite-temperature-time",
  "term": "NVMe Critical Composite Temperature Time",
  "aliases": [
    "CCTT",
    "critical_comp_time"
  ],
  "definition": "NVMe Critical Composite Temperature Time is a cumulative SMART / Health log duration in minutes of controller operation with Composite Temperature at or above the critical composite-temperature threshold.",
  "note": "NVMe Base 2.3 Figure 210 defines the threshold as CCTEMP from Identify Controller; if CCTEMP is zero, this timer is always zero regardless of Composite Temperature. [base23] It is separate from Warning Composite Temperature Time, from HCTM action timers measured in seconds, and from the current Critical Warning temperature bit, which can reflect an over-temperature or under-temperature condition. [base23]",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "The timer is not a shutdown count, a damage measurement or a calibrated failure probability; zero does not prove the drive has never been hot.",
      "citationIds": [
        "base23"
      ]
    }
  ],
  "related": [
    "nvme-composite-temperature",
    "nvme-warning-composite-temperature-time",
    "host-controlled-thermal-management",
    "nvme-smart-log",
    "nvme-critical-warning",
    "thermal-throttling-ssd"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "base23",
      "title": "NVM Express Base Specification 2.3, Figure 210, printed pp. 214, 216-217: temperature conditions and timers",
      "url": "https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-Revision-2.3-2025.08.01-Ratified.pdf",
      "accessed": "2026-10-16"
    }
  ],
  "updated": "2026-10-16"
}