1.4. GFS Software Subsystems

GFS consists of the following subsystems: GFS and GNBD.

Table 1-1 summarizes the GFS Software subsystems and their components.

Software SubsystemComponentsDescription
GFSgfs.koKernel module that implements the GFS file system and is loaded on GFS cluster nodes.
 gfs_fsckCommand that repairs an unmounted GFS file system.
 gfs_growCommand that grows a mounted GFS file system.
 gfs_jaddCommand that adds journals to a mounted GFS file system.
 gfs_mkfsCommand that creates a GFS file system on a storage device.
 gfs_quotaCommand that manages quotas on a mounted GFS file system.
 gfs_toolCommand that configures or tunes a GFS file system. This command can also gather a variety of information about the file system.
 lock_harness.koImplements a pluggable lock module interface for GFS that allows for a variety of locking mechanisms to be used (for example, the DLM lock module, lock_dlm.ko).
 lock_dlm.koA lock module that implements DLM locking for GFS. It plugs into the lock harness, lock_harness.ko and communicates with the DLM lock manager in Red Hat Cluster Suite.
 lock_gulm.koA lock module that implements GULM locking for GFS. It plugs into the lock harness, lock_harness.ko and communicates with the GULM lock manager in Red Hat Cluster Suite.
 lock_nolock.koA lock module for use when GFS is used as a local file system only. It plugs into the lock harness, lock_harness.ko and provides local locking.
GNBDgnbd.koKernel module that implements the GNBD device driver on clients.
 gnbd_exportCommand to create, export and manage GNBDs on a GNBD server.
 gnbd_importCommand to import and manage GNBDs on a GNBD client.
 gnbd_servA server daemon that allows a node to export local storage over the network.

Table 1-1. GFS Software Subsystem Components