Documentation/filesystems/gfs2.txt

   1 Global File System
   2 ------------------
   3
   4 http://sources.redhat.com/cluster/
   5
   6 GFS is a cluster file system. It allows a cluster of computers to
   7 simultaneously use a block device that is shared between them (with FC,
   8 iSCSI, NBD, etc).  GFS reads and writes to the block device like a local
   9 file system, but also uses a lock module to allow the computers coordinate
  10 their I/O so file system consistency is maintained.  One of the nifty
  11 features of GFS is perfect consistency -- changes made to the file system
  12 on one machine show up immediately on all other machines in the cluster.
  13
  14 GFS uses interchangable inter-node locking mechanisms.  Different lock
  15 modules can plug into GFS and each file system selects the appropriate
  16 lock module at mount time.  Lock modules include:
  17
  18   lock_nolock -- allows gfs to be used as a local file system
  19
  20   lock_dlm -- uses a distributed lock manager (dlm) for inter-node locking
  21   The dlm is found at linux/fs/dlm/
  22
  23 In addition to interfacing with an external locking manager, a gfs lock
  24 module is responsible for interacting with external cluster management
  25 systems.  Lock_dlm depends on user space cluster management systems found
  26 at the URL above.
  27
  28 To use gfs as a local file system, no external clustering systems are
  29 needed, simply:
  30
  31   $ mkfs -t gfs2 -p lock_nolock -j 1 /dev/block_device
  32   $ mount -t gfs2 /dev/block_device /dir
  33
  34 GFS2 is not on-disk compatible with previous versions of GFS.
  35
  36 The following man pages can be found at the URL above:
  37   gfs2_fsck     to repair a filesystem
  38   gfs2_grow     to expand a filesystem online
  39   gfs2_jadd     to add journals to a filesystem online
  40   gfs2_tool     to manipulate, examine and tune a filesystem
  41   gfs2_quota    to examine and change quota values in a filesystem
  42   mount.gfs2    to help mount(8) mount a filesystem
  43   mkfs.gfs2     to make a filesystem