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