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Documentation / filesystems / gfs2.txt




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Based on kernel version 2.6.33. Page generated on 2010-02-24 15:36 EST.

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, the currently
15	supported 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	
22	Lock_dlm depends on user space cluster management systems found
23	at the URL above.
24	
25	To use gfs as a local file system, no external clustering systems are
26	needed, simply:
27	
28	  $ mkfs -t gfs2 -p lock_nolock -j 1 /dev/block_device
29	  $ mount -t gfs2 /dev/block_device /dir
30	
31	If you are using Fedora, you need to install the gfs2-utils package
32	and, for lock_dlm, you will also need to install the cman package
33	and write a cluster.conf as per the documentation.
34	
35	GFS2 is not on-disk compatible with previous versions of GFS, but it
36	is pretty close.
37	
38	The 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
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