{
  "slug": "usable-capacity",
  "term": "Usable capacity",
  "aliases": [
    "Formatted capacity"
  ],
  "definition": "Usable capacity is the total configured capacity available to hold data after formatting and storage-system overhead.",
  "note": "Accounting: Usable capacity is also called formatted capacity. It excludes space committed to system functions, spares, parity and similar overhead. Some normally reserved areas can count when administrators can instead configure them for ordinary data. [snia-usable] [snia-formatted]\n\nHeadroom: Usable describes a total, not the free remainder after existing data and reservations. Record the configuration and the layer being measured before comparing a filesystem counter with an array capacity. [snia-formatted] [ontap-capacity]",
  "status": "unknown",
  "advantages": [],
  "limitations": [],
  "related": [
    "raw-capacity",
    "effective-capacity",
    "thin-provisioning",
    "raid"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "snia-usable",
      "title": "SNIA Dictionary: usable capacity",
      "url": "https://www.snia.org/education/online-dictionary/term/usable-capacity",
      "accessed": "2026-10-22"
    },
    {
      "id": "snia-formatted",
      "title": "SNIA Dictionary: formatted capacity",
      "url": "https://www.snia.org/education/online-dictionary/term/formatted-capacity",
      "accessed": "2026-10-22"
    },
    {
      "id": "ontap-capacity",
      "title": "NetApp ONTAP: capacity reporting and measurements",
      "url": "https://docs.netapp.com/us-en/ontap/concepts/capacity-measurements.html",
      "accessed": "2026-10-22"
    }
  ],
  "updated": "2026-10-22",
  "provenance": [
    "Terminology follows the cited accounting convention; no storage-array measurement or capacity guarantee is implied."
  ]
}