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+Global File System
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+------------------
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+
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+http://sources.redhat.com/cluster/
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+
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+GFS is a cluster file system. It allows a cluster of computers to
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+simultaneously use a block device that is shared between them (with FC,
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+iSCSI, NBD, etc). GFS reads and writes to the block device like a local
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+file system, but also uses a lock module to allow the computers coordinate
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+their I/O so file system consistency is maintained. One of the nifty
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+features of GFS is perfect consistency -- changes made to the file system
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+on one machine show up immediately on all other machines in the cluster.
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+
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+GFS uses interchangable inter-node locking mechanisms. Different lock
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+modules can plug into GFS and each file system selects the appropriate
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+lock module at mount time. Lock modules include:
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+
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+ lock_nolock -- allows gfs to be used as a local file system
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+
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+ lock_dlm -- uses a distributed lock manager (dlm) for inter-node locking
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+ The dlm is found at linux/fs/dlm/
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+
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+In addition to interfacing with an external locking manager, a gfs lock
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+module is responsible for interacting with external cluster management
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+systems. Lock_dlm depends on user space cluster management systems found
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+at the URL above.
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+
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+To use gfs as a local file system, no external clustering systems are
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+needed, simply:
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+
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+ $ gfs2_mkfs -p lock_nolock -j 1 /dev/block_device
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+ $ mount -t gfs2 /dev/block_device /dir
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+
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+GFS2 is not on-disk compatible with previous versions of GFS.
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+
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+The following man pages can be found at the URL above:
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+ gfs2_mkfs to make a filesystem
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+ gfs2_fsck to repair a filesystem
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+ gfs2_grow to expand a filesystem online
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+ gfs2_jadd to add journals to a filesystem online
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+ gfs2_tool to manipulate, examine and tune a filesystem
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+ gfs2_quota to examine and change quota values in a filesystem
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+ mount.gfs2 to find mount options
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+
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David Teigland