{
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-23",
  "slug": "storage-spaces-direct",
  "term": "Storage Spaces Direct",
  "aliases": [
    "S2D"
  ],
  "definition": "Storage Spaces Direct combines server-local drives into clustered software-defined storage using Storage Spaces and Windows clustering.",
  "note": "The architecture combines clustering, SMB communication, a Software Storage Bus and shared-volume access. It is not another name for ReFS or for a standalone storage pool. [spaces-direct]\n\nIts server-side pool cache operates at the drive layer, below volume resiliency. Cache-device selection and read/write behavior depend on the drive configuration; homogeneous drive types do not automatically create dedicated cache drives. This cache is separate from ReFS mirror-to-parity rotation. [spaces-cache]\n\nWhen a cache is configured, flash capacity uses write-only caching by default; HDD capacity uses read/write caching. Reads of newly written, undestaged data can still come from a write-only cache. Cache drives do not add usable cluster capacity. Cache persistence is not another replica: recovery after a cache-drive failure relies on surviving copies elsewhere. [spaces-cache]",
  "related": [
    "storage-spaces",
    "mirror-accelerated-parity",
    "refs",
    "smb-protocol",
    "failure-domain",
    "storage-bus-cache"
  ],
  "citations": [
    {
      "id": "spaces-direct",
      "title": "Microsoft Learn: Storage Spaces Direct architecture",
      "url": "https://learn.microsoft.com/en-us/windows-server/storage/storage-spaces/storage-spaces-direct-overview",
      "accessed": "2026-10-23"
    },
    {
      "id": "spaces-cache",
      "title": "Microsoft Learn: Storage pool cache at the drive layer",
      "url": "https://learn.microsoft.com/en-us/windows-server/storage/storage-spaces/cache",
      "accessed": "2026-10-23"
    }
  ],
  "provenance": [
    "Describes the documented clustered architecture, not a claim that every Windows edition or hardware configuration supports it. No cluster was deployed or benchmarked."
  ]
}