{
  "slug": "shared-disk-filesystem",
  "term": "Shared-disk file system",
  "aliases": [
    "shared-disk filesystem",
    "shared-storage file system"
  ],
  "definition": "A shared-disk file system coordinates concurrent file access by multiple hosts that can reach the same underlying block storage.",
  "note": "The shared block device supplies access to bytes; the file-system cluster must coordinate metadata changes and cached state across hosts. Each participating host operates the shared-disk file system over common block storage, rather than merely consuming a remote file service [rhel-filesystems].\n\nGFS2 is a concrete Linux example. Its cluster-wide locking uses the Distributed Lock Manager; its glock layer manages local caching in relation to cluster locks. Relinquishing an exclusive glock requires log flushing, dirty-data writeback and cache invalidation, so access that moves between nodes can incur coordination work even when the storage is healthy [rhel-gfs2].\n\nLocking during normal operation and exclusion during failure recovery are separate requirements. A GFS2 cluster requires fencing to exclude a failed or isolated node from shared storage before recovery; unsuccessful fencing can leave the cluster waiting. A shared-disk file system also does not replace application-level transaction coordination [rhel-gfs2].",
  "status": "shipping",
  "advantages": [
    {
      "text": "Provides coordinated file access across hosts sharing block storage, instead of treating each mount as an independent local file system.",
      "citationIds": [
        "rhel-filesystems"
      ]
    }
  ],
  "limitations": [
    {
      "text": "Requires the cluster's locking and failure-recovery infrastructure; shared reachability by itself provides neither.",
      "citationIds": [
        "rhel-gfs2"
      ]
    },
    {
      "text": "The shared storage remains a dependency: multiple attached hosts do not create independent data copies.",
      "citationIds": [
        "aws-multi-attach"
      ]
    }
  ],
  "related": [
    "file-storage",
    "block-storage",
    "san",
    "nas",
    "io-fencing"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-19",
  "citations": [
    {
      "id": "rhel-filesystems",
      "title": "Red Hat Enterprise Linux 8: Overview of available file systems, local, network and shared-storage categories",
      "url": "https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/html/managing_file_systems/overview-of-available-file-systems_managing-file-systems",
      "accessed": "2026-10-19"
    },
    {
      "id": "rhel-gfs2",
      "title": "Red Hat Enterprise Linux 8: Configuring GFS2 file systems, cluster configuration, fencing and glock caching",
      "url": "https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/html-single/configuring_gfs2_file_systems/index",
      "accessed": "2026-10-19"
    },
    {
      "id": "aws-multi-attach",
      "title": "Amazon EBS: Multi-Attach considerations and limitations (service-specific documentation)",
      "url": "https://docs.aws.amazon.com/ebs/latest/userguide/ebs-volumes-multi.html",
      "accessed": "2026-10-19"
    }
  ]
}