{
  "slug": "filesystem-quota",
  "term": "Filesystem quota",
  "aliases": [
    "disk quota"
  ],
  "definition": "A filesystem quota accounts for and can limit storage usage by a user, group or project within a filesystem.",
  "note": "Space and inode limits are distinct. With enforcement active, a soft limit permits an excess for a grace period, subject to the hard limit and other constraints. After expiry, further allocation of that resource is blocked until usage falls below the soft limit or policy changes. Hard-limit privilege exceptions depend on the implementation. [quota-kernel] [quotactl]\n\nXFS separates quota accounting from enforcement, so recorded usage alone does not show that allocation limits are active. [xfs-quota] Linux write() reports exhausted block quota as EDQUOT, separately from ENOSPC for insufficient data space. [quota-write]",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "An allocation ceiling is not a reservation of capacity in the filesystem or its backing thin pool.",
      "citationIds": [
        "hesela-capacity"
      ]
    }
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-21",
  "related": [
    "statvfs",
    "inode",
    "file-preallocation",
    "thin-provisioning"
  ],
  "provenance": [
    "Linux API and quota documentation review; supported quota types and enforcement depend on the filesystem. [quotactl]"
  ],
  "citations": [
    {
      "id": "quotactl",
      "title": "Linux man-pages: quotactl(2), user, group and project limits",
      "url": "https://man7.org/linux/man-pages/man2/quotactl.2.html",
      "accessed": "2026-10-21"
    },
    {
      "id": "quota-kernel",
      "title": "Linux kernel: quota subsystem, space/inode limits and grace periods",
      "url": "https://docs.kernel.org/filesystems/quota.html",
      "accessed": "2026-10-21"
    },
    {
      "id": "quota-write",
      "title": "Linux man-pages: write(2), EDQUOT, ENOSPC and partial writes",
      "url": "https://man7.org/linux/man-pages/man2/write.2.html",
      "accessed": "2026-10-21"
    },
    {
      "id": "xfs-quota",
      "title": "XFS: xfs_quota(8), accounting versus enforcement",
      "url": "https://man7.org/linux/man-pages/man8/xfs_quota.8.html",
      "accessed": "2026-10-21"
    },
    {
      "id": "hesela-capacity",
      "title": "Hesela: filesystem quotas and capacity headroom",
      "url": "https://hesela.com/analyses/sparse-files-preallocation-thin-capacity/#quota-headroom",
      "accessed": "2026-10-21"
    }
  ]
}