{
  "slug": "fail-slow",
  "term": "Fail-slow",
  "aliases": [
    "fail-slow failure",
    "hardware performance fault"
  ],
  "definition": "Fail-slow describes a component that remains operational but performs more slowly than expected for its operating conditions.",
  "note": "A slowdown is an observed performance symptom, not proof of a particular physical defect or imminent fail-stop event. Hardware, firmware and workload context must be separated. Gray failure additionally concerns a disagreement between application and system observations. [gunawi-fast18] [huang-hotos17]",
  "related": [
    "gray-failure",
    "differential-observability",
    "io-timeout"
  ],
  "citations": [
    {
      "id": "gunawi-fast18",
      "title": "Gunawi et al., Fail-Slow at Scale, FAST 2018; hardware performance faults and study limits.",
      "url": "https://www.usenix.org/system/files/conference/fast18/fast18-gunawi.pdf",
      "accessed": "2026-10-13"
    },
    {
      "id": "huang-hotos17",
      "title": "Huang et al., Gray Failure: The Achilles' Heel of Cloud-Scale Systems, HotOS 2017, section 3; DOI 10.1145/3102980.3103005.",
      "url": "https://www.microsoft.com/en-us/research/wp-content/uploads/2017/06/paper-1.pdf",
      "accessed": "2026-10-13"
    },
    {
      "id": "hesela-observers",
      "title": "Hesela: Fail-slow NVMe SSDs: what SMART and heartbeats miss",
      "url": "https://hesela.com/analyses/nvme-fail-slow-unseen-by-smart/",
      "accessed": "2026-10-13"
    }
  ],
  "status": "unknown",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-13"
}