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Documentation / filesystems / gfs2.txt




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Based on kernel version 3.9. Page generated on 2013-05-02 23:06 EST.

1	Global File System
2	------------------
3	
4	https://fedorahosted.org/cluster/wiki/HomePage
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 interchangeable 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. For F17 and above
34	cman has been replaced by the dlm package.
35	
36	GFS2 is not on-disk compatible with previous versions of GFS, but it
37	is pretty close.
38	
39	The following man pages can be found at the URL above:
40	  fsck.gfs2		to repair a filesystem
41	  gfs2_grow		to expand a filesystem online
42	  gfs2_jadd		to add journals to a filesystem online
43	  tunegfs2		to manipulate, examine and tune a filesystem
44	  gfs2_convert	to convert a gfs filesystem to gfs2 in-place
45	  mkfs.gfs2		to make a filesystem
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