The Resilient Storage Add-On provides numerous file system capabilities for improving resiliency to system failure. GFS2 is a shared storage file system - often referred to as a cluster file system - that gives each server in a cluster direct access to a shared block device over a local storage area network (SAN) of up to 100 terabytes. Each member of the cluster has direct access to the same storage device, and all cluster nodes access the same set of files.
Because a clustered file system like GFS2 requires cache consistency to insure data consistency and integrity, there must be a single version of all files in a cluster visible to all nodes within that cluster. To prevent members of the cluster from updating the same storage block at the same time in a way that corrupts data, GFS2 uses a cluster-wide locking mechanism called Distributed Lock Manager (DLM) to arbitrate access to the storage as a concurrency control mechanism.
GFS2 shared storage file system
GFS2 is a clustered file system in which data is shared among GFS2 nodes with a single, consistent, and coherent view of the file system name space. Processes on different nodes may work with GFS2 files in the same way that processes on one node can share files in a local file system.
Cluster Logical Volume Manager (CLVM)
CLVM provides the same capabilities as LVM2 on a single node, but makes the volumes available to all nodes in a Red Hat cluster. The logical volumes created with CLVM make logical volumes available to all nodes in a cluster.
Clustered Samba (tech preview)
Clustered Samba enables exporting of a GFS2 file system through one or more nodes in the cluster in an active/passive or active/active configuration.