Before Configuring Global Clusters

This section describes the prerequisites for configuring global clusters.

Cluster Setup

You must have at least two clusters to set up a global cluster. Every cluster must have the VCS Global Cluster Option license installed. 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 for more information.

Configured Applications

Applications to be configured as global groups must be configured to represent each other in their respective clusters. The multiple application groups of a global group must have the same name in each cluster. The individual resources of the groups can be different. For example, one group might have a MultiNIC resource or more Mount-type resources. Clients redirected to the remote cluster in case of a wide-area failover must be presented with the same application they saw in the primary cluster.

However, the resources that make up a global group must represent the same application from the point of the client as its peer global group in the other cluster. Clients redirected to a remote cluster should not be aware that a cross-cluster failover occurred, except for some downtime while the administrator initiates or confirms the failover.

Wide-Area Heartbeats

There must be at least one wide-area heartbeat going from each cluster to every other cluster. VCS starts communicating with a cluster only after the heartbeat reports that the cluster is alive. VCS uses the ICMP ping by default, the infrastructure for which is bundled with the product. VCS configures the ICMP heartbeat if you use Cluster Manager (Java Console) to set up your global cluster. Other heartbeats must be configured manually.

ClusterService Group

The ClusterService group must be configured with the wac, NIC, and IP resources. It is configured automatically when VCS is installed or upgraded, or by the GCO configuration wizard. The service group may contain additional resources for Cluster Manager (Web Console) and notification, if these components are configured.

If you entered a Global Cluster Option license during the VCS install or upgrade, the ClusterService group, including the wide-area connector process, is automatically configured.

If you add the license after VCS is operational, you must run the GCO Configuration wizard. For instructions, see Running the GCO Configuration Wizard.

Replication Setup

VCS global clusters are also used in case of disaster recovery, so you must set up real-time data replication between clusters. You can use VCS agents for supported replication solutions to manage the replication. If your configuration uses VERITAS Volume Replicator, you must add the VTRSvcsr package to all systems.