| David Teigland | e473142 | 2006-01-18 09:21:38 +0000 | [diff] [blame^] | 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. Different lock |
| 15 | modules can plug into GFS and each file system selects the appropriate |
| 16 | lock module at mount time. Lock modules include: |
| 17 | |
| 18 | lock_nolock -- allows gfs to be used as a local file system |
| 19 | |
| 20 | lock_dlm -- uses a distributed lock manager (dlm) for inter-node locking |
| 21 | The dlm is found at linux/fs/dlm/ |
| 22 | |
| 23 | In addition to interfacing with an external locking manager, a gfs lock |
| 24 | module is responsible for interacting with external cluster management |
| 25 | systems. Lock_dlm depends on user space cluster management systems found |
| 26 | at the URL above. |
| 27 | |
| 28 | To use gfs as a local file system, no external clustering systems are |
| 29 | needed, simply: |
| 30 | |
| 31 | $ gfs2_mkfs -p lock_nolock -j 1 /dev/block_device |
| 32 | $ mount -t gfs2 /dev/block_device /dir |
| 33 | |
| 34 | GFS2 is not on-disk compatible with previous versions of GFS. |
| 35 | |
| 36 | The following man pages can be found at the URL above: |
| 37 | gfs2_mkfs to make a filesystem |
| 38 | gfs2_fsck to repair a filesystem |
| 39 | gfs2_grow to expand a filesystem online |
| 40 | gfs2_jadd to add journals to a filesystem online |
| 41 | gfs2_tool to manipulate, examine and tune a filesystem |
| 42 | gfs2_quota to examine and change quota values in a filesystem |
| 43 | mount.gfs2 to find mount options |
| 44 | |