1.. SPDX-License-Identifier: GPL-2.0 2 3==================== 4Global File System 2 5==================== 6 7Overview 8======== 9 10GFS2 is a cluster file system. It allows a cluster of computers to 11simultaneously use a block device that is shared between them (with FC, 12iSCSI, NBD, etc). GFS2 reads and writes to the block device like a local 13file system, but also uses a lock module to allow the computers coordinate 14their I/O so file system consistency is maintained. One of the nifty 15features of GFS2 is perfect consistency -- changes made to the file system 16on one machine show up immediately on all other machines in the cluster. 17 18GFS2 uses interchangeable inter-node locking mechanisms, the currently 19supported mechanisms are: 20 21 lock_nolock 22 - allows GFS2 to be used as a local file system 23 24 lock_dlm 25 - uses the distributed lock manager (dlm) for inter-node locking. 26 The dlm is found at linux/fs/dlm/ 27 28lock_dlm depends on user space cluster management systems found 29at the URL above. 30 31To use GFS2 as a local file system, no external clustering systems are 32needed, simply:: 33 34 $ mkfs -t gfs2 -p lock_nolock -j 1 /dev/block_device 35 $ mount -t gfs2 /dev/block_device /dir 36 37The gfs2-utils package is required on all cluster nodes and, for lock_dlm, you 38will also need the dlm and corosync user space utilities configured as per the 39documentation. 40 41gfs2-utils can be found at https://pagure.io/gfs2-utils 42 43GFS2 is not on-disk compatible with previous versions of GFS, but it 44is pretty close. 45 46The following man pages are available from gfs2-utils: 47 48 ============ ============================================= 49 fsck.gfs2 to repair a filesystem 50 gfs2_grow to expand a filesystem online 51 gfs2_jadd to add journals to a filesystem online 52 tunegfs2 to manipulate, examine and tune a filesystem 53 gfs2_convert to convert a gfs filesystem to GFS2 in-place 54 mkfs.gfs2 to make a filesystem 55 ============ ============================================= 56 57Implementation Notes 58==================== 59 60.. toctree:: 61 :maxdepth: 1 62 63 glocks 64 uevents 65