Documentation/filesystems/gfs2.rst

   1 .. SPDX-License-Identifier: GPL-2.0
   2
   3 ==================
   4 Global File System
   5 ==================
   6
   7 https://fedorahosted.org/cluster/wiki/HomePage
   8
   9 GFS is a cluster file system. It allows a cluster of computers to
  10 simultaneously use a block device that is shared between them (with FC,
  11 iSCSI, NBD, etc).  GFS reads and writes to the block device like a local
  12 file system, but also uses a lock module to allow the computers coordinate
  13 their I/O so file system consistency is maintained.  One of the nifty
  14 features of GFS is perfect consistency -- changes made to the file system
  15 on one machine show up immediately on all other machines in the cluster.
  16
  17 GFS uses interchangeable inter-node locking mechanisms, the currently
  18 supported mechanisms are:
  19
  20   lock_nolock
  21     - allows gfs to be used as a local file system
  22
  23   lock_dlm
  24     - uses a distributed lock manager (dlm) for inter-node locking.
  25       The dlm is found at linux/fs/dlm/
  26
  27 Lock_dlm depends on user space cluster management systems found
  28 at the URL above.
  29
  30 To use gfs as a local file system, no external clustering systems are
  31 needed, simply::
  32
  33   $ mkfs -t gfs2 -p lock_nolock -j 1 /dev/block_device
  34   $ mount -t gfs2 /dev/block_device /dir
  35
  36 If you are using Fedora, you need to install the gfs2-utils package
  37 and, for lock_dlm, you will also need to install the cman package
  38 and write a cluster.conf as per the documentation. For F17 and above
  39 cman has been replaced by the dlm package.
  40
  41 GFS2 is not on-disk compatible with previous versions of GFS, but it
  42 is pretty close.
  43
  44 The following man pages can be found at the URL above:
  45
  46   ============          =============================================
  47   fsck.gfs2             to repair a filesystem
  48   gfs2_grow             to expand a filesystem online
  49   gfs2_jadd             to add journals to a filesystem online
  50   tunegfs2              to manipulate, examine and tune a filesystem
  51   gfs2_convert          to convert a gfs filesystem to gfs2 in-place
  52   mkfs.gfs2             to make a filesystem
  53   ============          =============================================