Enterprise Vault RPC Extensions are supported on clustered RPC target Exchange Virtual Servers (Exchange Server 2003).

In active/passive Exchange Virtual Server cluster configurations, you must install the Exchange 2003 Back-end Extensions (OWA & RPC) on both active and passive nodes; you can install them on either an active or passive node first.

Figure: RPC extensions configuration shows the location of the various virtual directories and configuration data used by the extensions.