"Running GFS means you are running a cluster. By far the easiest way to accomplish this is by using the Red Hat (NYSE: RHT) Cluster Suite (RHCS), available in CentOS 5. The following packages are required: cman, the cluster manager; lvm2-cluster, the CLVM package to enable cluster support in LVM; kmod-gfs, the GFS kernel module; and finally gfs-utils.
"The cluster manager (cman) takes care of necessities like the distributed lock manager and fencing. Using CentOS or RHEL is highly recommended unless you want to spend time figuring out how the various distros broke the cman package when they adopted it (they always do). Also, you will get the most recent release of the various cluster services RH maintains, along with a predictable environment.
"Fencing is absolutely required. Some how-to articles recommend setting the fence mode to "manual" because it can be complex to configure. Fencing means partitioning a cluster, or immediately powering off dangerous nodes. You will have a corrupt GFS if the cluster is unable to fence a misbehaving node, so do not skip this step."
