{
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "A zero is not proof that a drive never ran hot; this counter is neither a complete temperature history nor a failure-probability estimate.",
      "citationIds": [
        "base23",
        "nvmelog"
      ]
    }
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-16",
  "slug": "nvme-warning-composite-temperature-time",
  "term": "NVMe Warning Composite Temperature Time",
  "aliases": [
    "WCTT",
    "warning_temp_time"
  ],
  "definition": "NVMe Warning Composite Temperature Time is a cumulative health-log duration in minutes governed by composite-temperature thresholds and, in supporting revisions and configurations, temperature hysteresis.",
  "note": "Base 2.3 Figure 210 defines controller-operational time with WCTEMP <= Composite Temperature < CCTEMP when TMPTHHA is zero and includes hysteresis time when TMPTHMH and TMPTHH are nonzero. Either WCTEMP or CCTEMP being zero forces this field to zero. [base23] It is distinct from Critical Composite Temperature Time and from the HCTM action timers, which use seconds. [nvmelog]",
  "related": [
    "nvme-composite-temperature",
    "nvme-smart-log",
    "host-controlled-thermal-management",
    "thermal-throttling-ssd",
    "nvme-critical-composite-temperature-time"
  ],
  "citations": [
    {
      "id": "base23",
      "title": "NVM Express Base Specification 2.3: Figure 210 (pp. 214-217), temperature hysteresis section 5.2.26.1.3.1, HCTM Figure 417 (p. 410)",
      "url": "https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-Revision-2.3-2025.08.01-Ratified.pdf",
      "accessed": "2026-10-15"
    },
    {
      "id": "nvmelog",
      "title": "libnvme v1.15: nvme_smart_log field definitions (July 2025)",
      "url": "https://github.com/linux-nvme/libnvme/blob/v1.15/doc/man/nvme_smart_log.2",
      "accessed": "2026-10-15"
    }
  ]
}