Figure: Clustered Exchange Server 2000/2003 OWA example gives an example of an active/passive cluster of Exchange Servers.

The following clustering examples relate only to Exchange Server 2000 and 2003 OWA configurations. In an Exchange Server 2007 or 2010 OWA environment, the Mailbox server can be clustered, but the CAS server cannot. As it is the CAS server that contacts the Enterprise Vault server, the Enterprise Vault configuration is unaffected when Exchange Server 2007 or 2010 Mailbox servers are clustered.

Figure: Clustered Exchange Server 2000/2003 OWA example

In this configuration, Enterprise Vault OWA 2000 or 2003 Extensions must be installed and configured on both Exchange Servers in the cluster. Enterprise Vault automatically adds the necessary cluster addresses to its configuration files when you configure the OWA Extensions. There could also be a front-end Exchange Server, but this would not normally be included in a cluster configuration.

When one Exchange Server in the cluster fails over to the other, connections to the Enterprise Vault servers are established automatically; users can continue to access items in their Enterprise Vault archives.

Figure: Configuration after failover

See About OWA configurations for Enterprise Vault