Chapter 8. Global File System 2
The Red Hat GFS2 file system is a native file system that interfaces directly with the Linux kernel file system interface (VFS layer). When implemented as a cluster file system, GFS2 employs distributed metadata and multiple journals.
GFS2 is based on a 64-bit architecture, which can theoretically accommodate an 8 EB file system. However, the current supported maximum size of a GFS2 file system is 100 TB. If your system requires GFS2 file systems larger than 100 TB, contact your Red Hat service representative.
When determining the size of your file system, you should consider your recovery needs. Running the fsck command on a very large file system can take a long time and consume a large amount of memory. Additionally, in the event of a disk or disk-subsytem failure, recovery time is limited by the speed of your backup media.
When configured in a Red Hat Cluster Suite, Red Hat GFS2 nodes can be configured and managed with Red Hat Cluster Suite configuration and management tools. Red Hat GFS2 then provides data sharing among GFS2 nodes in a Red Hat cluster, with a single, consistent view of the file system name space across the GFS2 nodes. This allows processes on different nodes to share GFS2 files in the same way that processes on the same node can share files on a local file system, with no discernible difference. For information about the Red Hat Cluster Suite, refer to Configuring and Managing a Red Hat Cluster.
A GFS2 file system must be created on an LVM logical volume that is a linear or mirrored volume. LVM logical volumes in a Red Hat Cluster suite are managed with CLVM, which is a cluster-wide implementation of LVM, enabled by the CLVM daemon, clvmd, running in a Red Hat Cluster Suite cluster. The daemon makes it possible to use LVM2 to manage logical volumes across a cluster, allowing all nodes in the cluster to share the logical volumes. For information on the LVM volume manager, see Logical Volume Manager Administration.
The gfs2.ko kernel module implements the GFS2 file system and is loaded on GFS2 cluster nodes.
For comprehensive information on the creation and configuration of GFS2 file systems in clustered and non-clustered storage, please refer to the Global File System 2 guide also provided by Red Hat.
