{
  "slug": "glass-storage",
  "term": "Glass storage",
  "aliases": [
    "Project Silica",
    "volumetric glass archive"
  ],
  "definition": "Experimental archival storage that encodes data as structural changes inside glass for very long-duration, read-mostly retention.",
  "note": "Glass archival research (Microsoft Project Silica is the best-known public program) encodes data inside durable quartz/fused silica using ultrafast femtosecond lasers that write volumetric voxels, then reads with polarization-sensitive microscopy. The media is write-once (WORM) by design: read optics lack the energy to rewrite the glass, and library mechanics can keep plates out of writers for an air-gap archive. Public materials describe research prototypes and demonstrators (including cloud-library concepts), not a general retail glass-drive SKU line. Scope is long-horizon archival media exploration alongside tape and optical disc—capacity, write rate, and lifetime figures must be taken from the cited research papers, not secondary marketing summaries.",
  "status": "research",
  "advantages": [
    {
      "text": "Demonstrated multi-layer writes in silica with no moving media during read.",
      "citationIds": [
        "c1"
      ]
    }
  ],
  "limitations": [
    {
      "text": "Not a shipping general-purpose replacement for tape or HDD at datacenter scale.",
      "citationIds": [
        "c1"
      ]
    }
  ],
  "related": [
    "optical-archival",
    "hot-warm-cold"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "c1",
      "title": "Project Silica",
      "url": "https://www.microsoft.com/en-us/research/project/project-silica/",
      "accessed": "2026-03-26"
    },
    {
      "id": "n2",
      "title": "Microsoft Research — Project Silica: Towards Sustainable Cloud Archival Storage in Glass (SOSP 2023 PDF)",
      "url": "https://www.microsoft.com/en-us/research/wp-content/uploads/2023/09/ProjectSilica-SOSP23.pdf",
      "accessed": "2026-10-07"
    },
    {
      "id": "n3",
      "title": "Microsoft Research — Project Silica’s advances in glass storage technology (blog)",
      "url": "https://www.microsoft.com/en-us/research/blog/project-silicas-advances-in-glass-storage-technology/",
      "accessed": "2026-10-07"
    }
  ]
}