In computing, the Global File System (GFS) is a shared disk file system for Linux computer clusters.GFS differs from distributed file systems (such as AFS, Coda, or InterMezzo) because it allows all nodes to have direct concurrent access to the same shared block storage.

GFS has no disconnected operating-mode, and no client or server roles. All nodes in a GFS cluster function as peers. System administrators often use Fibre Channel, iSCSI, or AoE devices for GFS shared storage. Using GFS in a cluster requires a lock manager plug-in like GULM, a server based lock manager which implements redundancy via failover, or a Distributed Lock Manager (DLM) which is the current preferred approach. There is also a "nolock" lock manager which can be used in single node deployments when GFS acts just like any other local filesystem. GFS comes as free software, distributed under the terms of the GNU General Public License.

GFS was originally developed as part of a thesis-project at the University of Minnesota in 1997. It was originally written for SGI's IRIX operating system, but in 1998 it was ported to Linux since the open source code provided a more convenient development platform. In late 1999/early 2000 it made its way to Sistina Software, where it lived for a time as an open-source project. Sometime in 2001 Sistina made the choice to make GFS a commercial product — not under an open-source license.

Developers forked OpenGFS from the last public release of GFS and then further enhanced it to include updates allowing it to work with OpenDLM. But OpenGFS and OpenDLM became defunct, since Red Hat purchased Sistina in December 2003 and released GFS and many cluster infrastructure pieces under the GPL in late June 2004.

As of 2007, GFS forms part of the Fedora and CentOS Linux distributions. Users can purchase commercial support to run GFS fully supported on top of Red Hat Enterprise Linux. Since Red Hat Enterprise Linux version 5, GFS support is already included with RHEL Advanced Platform at no additional cost.