Achieving Robust Clustered Storage with Linux and GFS

“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.”

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