.. SPDX-License-Identifier: GPL-2.0
====================
Global File System 2
====================
GFS2 is a cluster file system. It allows a cluster of computers to
simultaneously use a block device that is shared between them (with FC,
iSCSI, NBD, etc). GFS2 reads and writes to the block device like a local
file system, but also uses a lock module to allow the computers coordinate
their I/O so file system consistency is maintained. One of the nifty
features of GFS2 is perfect consistency -- changes made to the file system
on one machine show up immediately on all other machines in the cluster.
GFS2 uses interchangeable inter-node locking mechanisms, the currently
supported mechanisms are:
lock_nolock
- allows GFS2 to be used as a local file system
lock_dlm
- uses the distributed lock manager (dlm) for inter-node locking.
The dlm is found at linux/fs/dlm/
lock_dlm depends on user space cluster management systems found
at the URL above.
To use GFS2 as a local file system, no external clustering systems are
needed, simply::
$ mkfs -t gfs2 -p lock_nolock -j 1 /dev/block_device
$ mount -t gfs2 /dev/block_device /dir
The gfs2-utils package is required on all cluster nodes and, for lock_dlm, you
will also need the dlm and corosync user space utilities configured as per the
documentation.
gfs2-utils can be found at
https://pagure.io/gfs2-utils
GFS2 is not on-disk compatible with previous versions of GFS, but it
is pretty close.
The following man pages are available from gfs2-utils:
============ =============================================
fsck.gfs2 to repair a filesystem
gfs2_grow to expand a filesystem online
gfs2_jadd to add journals to a filesystem online
tunegfs2 to manipulate, examine and tune a filesystem
gfs2_convert to convert a gfs filesystem to GFS2 in-place
mkfs.gfs2 to make a filesystem
============ =============================================
