{
  "slug": "hierarchical-storage-management",
  "term": "Hierarchical storage management",
  "aliases": [
    "HSM"
  ],
  "definition": "Hierarchical storage management automates data migration between storage tiers according to policies that balance access needs, capacity and cost.",
  "note": "HSM places less active data on lower-cost storage so higher-performance capacity can serve active work. Inactivity is a common policy input, not a requirement to use tape or any fixed sequence of media. [snia-hsm]\n\nFile-based implementations can retain a local stub containing the information needed to locate and recall migrated data. Some metadata requests can be answered without fetching the payload. A pathname can therefore remain visible while its data is elsewhere. [hsm-migration]\n\nPremigration can retain the complete local file alongside its remote copy. In the documented client, later stubbing of premigrated files reclaims local space without resending their payload. A copied file is not necessarily a released file. [hsm-premigration]\n\nMigration changes placement; it does not by itself establish an independently retained recovery copy. Back up resident and migrated files according to the recovery requirement. Restoring a stub and restoring the complete file are different operations: recall through a restored stub still depends on an available, matching migration copy. [hsm-backup]\n\nFor recovery planning, check the namespace or stub metadata, backend payload and retrieval service together. Treat that as an engineering checklist, not a durability guarantee from an HSM label. [hsm-overview] [hsm-backup]\n\nHSM need not use whole-file stubs. HighLight's 1993 design used a common block address space and fetched whole tertiary segments. Its initial selection policy still used file-level information; finer access-range tracking was future work. Distinguish the transfer unit from the policy's observation unit. [hsm-highlight]",
  "status": "shipping",
  "related": [
    "hot-warm-cold",
    "lustre-hsm",
    "lustre-hsm-release",
    "cold-archive",
    "backup",
    "restore-test"
  ],
  "advantages": [],
  "limitations": [],
  "citations": [
    {
      "id": "snia-hsm",
      "title": "SNIA Dictionary: hierarchical storage management",
      "url": "https://www.snia.org/education/online-dictionary/term/hierarchical-storage-management",
      "accessed": "2026-11-09"
    },
    {
      "id": "hsm-migration",
      "title": "IBM Storage Protect for Space Management 8.2.0: Migrating files overview",
      "url": "https://www.ibm.com/docs/en/spfsm/8.2.0?topic=client-migrating-files-overview",
      "accessed": "2026-11-09"
    },
    {
      "id": "hsm-overview",
      "title": "IBM Storage Protect for Space Management 8.2.1: Overview of the space management client",
      "url": "https://www.ibm.com/docs/en/spfsm/8.2.1?topic=overview-space-management-client",
      "accessed": "2026-11-09"
    },
    {
      "id": "hsm-backup",
      "title": "IBM Storage Protect for Space Management 8.2.1: Backup and restore on space managed file systems",
      "url": "https://www.ibm.com/docs/en/spfsm/8.2.1?topic=systems-backup-restore-space-managed-file",
      "accessed": "2026-11-09"
    },
    {
      "id": "hsm-premigration",
      "title": "IBM Storage Protect for Space Management 8.1.27: dsmmigrate",
      "url": "https://www.ibm.com/docs/en/spfsm/8.1.27?topic=reference-dsmmigrate",
      "accessed": "2026-11-09"
    },
    {
      "id": "hsm-highlight",
      "title": "Kohl, Stonebraker and Staelin (1993): HighLight: a file system for tertiary storage (author-uploaded full text)",
      "url": "https://www.researchgate.net/publication/2249371_Highlight_A_File_System_For_Tertiary_Storage",
      "accessed": "2026-11-09"
    }
  ],
  "provenance": [
    "SNIA supplies the general concept; IBM manuals for 8.1.27, 8.2.0 and 8.2.1 supply implementation examples, not a universal stub format or recall mode.",
    "IBM documentation was read through indexed primary-source text; direct page requests returned HTTP 403. No HSM system or restore experiment was operated.",
    "The recovery-dependency checklist is an engineering inference. Human-facing context: https://hesela.com/analyses/snapshot-backup-recovery-boundaries/#hsm-placement",
    "HighLight's mechanism and policy sections were read in the author-uploaded full text. Publisher-linked DOI 10.1109/MASS.1993.289765 establishes 1993; the repository's 1996 label is not used as the publication year."
  ],
  "supersedes": [],
  "supersededBy": [],
  "updated": "2026-11-09"
}