You must have at least two clusters to set up a global cluster. Every cluster must have the required licenses. A cluster can be part of one global cluster. VCS supports a maximum of four clusters participating in a global cluster.
Clusters must be running on the same platform; the operating system versions can be different. Clusters must be using the same VCS version.
Cluster names must be unique within each global cluster; system and resource names need not be unique across clusters. Service group names need not be unique across clusters; however, global service groups must have identical names.
Every cluster must have a valid virtual IP address, which is tied to the cluster. Define this IP address in the cluster's ClusterAddress attribute. This address is normally configured as part of the initial VCS installation. The IP address must have a DNS entry.
For remote cluster operations, you must configure a VCS user with the same name and privileges in each cluster.
See User privileges in global clusters.