1.. SPDX-License-Identifier: GPL-2.0
2
3====================
4Global File System 2
5====================
6
7GFS2 is a cluster file system. It allows a cluster of computers to
8simultaneously use a block device that is shared between them (with FC,
9iSCSI, NBD, etc).  GFS2 reads and writes to the block device like a local
10file system, but also uses a lock module to allow the computers coordinate
11their I/O so file system consistency is maintained.  One of the nifty
12features of GFS2 is perfect consistency -- changes made to the file system
13on one machine show up immediately on all other machines in the cluster.
14
15GFS2 uses interchangeable inter-node locking mechanisms, the currently
16supported mechanisms are:
17
18  lock_nolock
19    - allows GFS2 to be used as a local file system
20
21  lock_dlm
22    - uses the distributed lock manager (dlm) for inter-node locking.
23      The dlm is found at linux/fs/dlm/
24
25lock_dlm depends on user space cluster management systems found
26at the URL above.
27
28To use GFS2 as a local file system, no external clustering systems are
29needed, simply::
30
31  $ mkfs -t gfs2 -p lock_nolock -j 1 /dev/block_device
32  $ mount -t gfs2 /dev/block_device /dir
33
34The gfs2-utils package is required on all cluster nodes and, for lock_dlm, you
35will also need the dlm and corosync user space utilities configured as per the
36documentation.
37
38gfs2-utils can be found at https://pagure.io/gfs2-utils
39
40GFS2 is not on-disk compatible with previous versions of GFS, but it
41is pretty close.
42
43The following man pages are available from gfs2-utils:
44
45  ============		=============================================
46  fsck.gfs2		to repair a filesystem
47  gfs2_grow		to expand a filesystem online
48  gfs2_jadd		to add journals to a filesystem online
49  tunegfs2		to manipulate, examine and tune a filesystem
50  gfs2_convert		to convert a gfs filesystem to GFS2 in-place
51  mkfs.gfs2		to make a filesystem
52  ============		=============================================
53