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- 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. Different lock
- modules can plug into GFS and each file system selects the appropriate
- lock module at mount time. Lock modules include:
- 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/
- In addition to interfacing with an external locking manager, a gfs lock
- module is responsible for interacting with external cluster management
- systems. 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
- GFS2 is not on-disk compatible with previous versions of GFS.
- The following man pages can be found at the URL above:
- gfs2_fsck 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
- mount.gfs2 to help mount(8) mount a filesystem
- mkfs.gfs2 to make a filesystem
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