Not so long ago we needed to create RHEL (not CentOS) cluster for the SAP/Oracle DB tandem, the documentation is indeed very poor and very lightly informative, the recommended way for creating the cluster config (
/etc/cluster/cluster.conf) is ... a graphical wizard (
system-cluster-config).
... and what is even more funny, when You create the fencing part of the config with
system-cluster-config, then close the wizard and start it again ... it yels about inproper config and quits
We needed to use ssh -X for that ocnfiguration many times, cause its either
system-cluster-config (X11) or
vi /etc/cluster/cluster.conf (which we prefer of course).
The configuration about clustered LVM was also very blurry and we managed to achieve what we needed mostly by try to change that and that and check if it works as advertised.
The support is also very doubtful if it comes to more advanced problems as clustering or using storage arrays with multipathing.
We ended many times using the
HP-UX documentation (or any other UNIX) on, for example, clustered HA-NFS instance (yes SAP requires NFS exported filesystems .. of local filesystems, but thats another story).