For every cluster type there is a set of required snap-ins that must be loaded so that they can be automatically installed on the cluster. If one or more of the required snap-ins is not loaded, the system displays a warning message. You cannot create or edit the cluster successfully.
In a closed cluster, you cannot install snap-ins that are not part of the optional or mandatory snap-in list.
If the snap-in being installed requires cluster database, a warning message is displayed that you must enable Cluster Database before the snap-in is installed. For more information, see Enabling Cluster Database
.