{
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-16",
  "slug": "nvme-host-identifier",
  "term": "NVMe Host Identifier",
  "aliases": [
    "NVMe Host ID",
    "HOSTID"
  ],
  "definition": "The NVMe Host Identifier identifies which controllers in an NVM subsystem belong to the same host for purposes including reservation rights.",
  "note": "Matching nonzero Host Identifiers group controllers under one host's reservation rights; the reservation key is separate. [nvme-base-20c] Base 2.3 treats zero identifiers on two controllers as different hosts. Zero-associated reservations and registrations do not survive Controller Level Reset, and changing zero to nonzero does not transfer those associations. Host Identifier is non-saveable; PCIe defaults to zero and NVMe over Fabrics requires 128 bits. [nvme-base-23-hostid] Do not extrapolate these lifecycle rules to all earlier or later NVMe versions.",
  "related": [
    "nvme-reservation",
    "multipath-nvme",
    "namespace-nvme"
  ],
  "citations": [
    {
      "id": "nvme-base-20c",
      "title": "NVM Express Base Specification 2.0c (2022), sections 5.27.1.25, 7.2-7.5 and 8.19. Copyright 2008-2022 NVM Express, Inc. All rights reserved.",
      "url": "https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-2.0c-2022.10.04-Ratified.pdf",
      "accessed": "2026-10-16"
    },
    {
      "id": "hesela-fencing",
      "title": "Storage fencing: why a lost heartbeat does not stop writes",
      "url": "https://hesela.com/analyses/storage-fencing-stale-writes/",
      "accessed": "2026-10-16"
    },
    {
      "id": "nvme-base-23-hostid",
      "title": "NVM Express Base Specification 2.3 (2025), section 5.2.26.1.32, pp. 438-440: Host Identifier and transport-specific lifecycle rules.",
      "url": "https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-Revision-2.3-2025.08.01-Ratified.pdf",
      "accessed": "2026-10-16"
    }
  ]
}