Global File System
  ------------------
  
  http://sources.redhat.com/cluster/
  
  GFS 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).  GFS 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 GFS is perfect consistency -- changes made to the file system
  on one machine show up immediately on all other machines in the cluster.

  GFS uses interchangable inter-node locking mechanisms, the currently
  supported mechanisms are:

  
    lock_nolock -- allows gfs to be used as a local file system
  
    lock_dlm -- uses a 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 gfs 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

  If you are using Fedora, you need to install the gfs2-utils package
  and, for lock_dlm, you will also need to install the cman package
  and write a cluster.conf as per the documentation.
  
  GFS2 is not on-disk compatible with previous versions of GFS, but it
  is pretty close.

  
  The following man pages can be found at the URL above:

    fsck.gfs2	to repair a filesystem

    gfs2_grow	to expand a filesystem online
    gfs2_jadd	to add journals to a filesystem online
    gfs2_tool	to manipulate, examine and tune a filesystem
    gfs2_quota	to examine and change quota values in a filesystem

    gfs2_convert	to convert a gfs filesystem to gfs2 in-place

    mount.gfs2	to help mount(8) mount a filesystem
    mkfs.gfs2	to make a filesystem