1Global File System 2------------------ 3 4http://sources.redhat.com/cluster/wiki/ 5 6GFS is a cluster file system. It allows a cluster of computers to 7simultaneously use a block device that is shared between them (with FC, 8iSCSI, NBD, etc). GFS reads and writes to the block device like a local 9file system, but also uses a lock module to allow the computers coordinate 10their I/O so file system consistency is maintained. One of the nifty 11features of GFS is perfect consistency -- changes made to the file system 12on one machine show up immediately on all other machines in the cluster. 13 14GFS uses interchangable inter-node locking mechanisms, the currently 15supported mechanisms are: 16 17 lock_nolock -- allows gfs to be used as a local file system 18 19 lock_dlm -- uses a distributed lock manager (dlm) for inter-node locking 20 The dlm is found at linux/fs/dlm/ 21 22Lock_dlm depends on user space cluster management systems found 23at the URL above. 24 25To use gfs as a local file system, no external clustering systems are 26needed, simply: 27 28 $ mkfs -t gfs2 -p lock_nolock -j 1 /dev/block_device 29 $ mount -t gfs2 /dev/block_device /dir 30 31If you are using Fedora, you need to install the gfs2-utils package 32and, for lock_dlm, you will also need to install the cman package 33and write a cluster.conf as per the documentation. 34 35GFS2 is not on-disk compatible with previous versions of GFS, but it 36is pretty close. 37 38The following man pages can be found at the URL above: 39 fsck.gfs2 to repair a filesystem 40 gfs2_grow to expand a filesystem online 41 gfs2_jadd to add journals to a filesystem online 42 gfs2_tool to manipulate, examine and tune a filesystem 43 gfs2_quota to examine and change quota values in a filesystem 44 gfs2_convert to convert a gfs filesystem to gfs2 in-place 45 mount.gfs2 to help mount(8) mount a filesystem 46 mkfs.gfs2 to make a filesystem 47