Some items of note regarding the Messaging Server and high availability (applies to both Veritas Cluster, and Sun Cluster) installation:
Clustering software needs to be installed before installing and configuring the current version of Messaging Server. Run the installation on the cluster node currently pointed at by the HA logical host name for Messaging Server. Use the cluster alias when prompted for any node names. When installing Messaging Server, tell the Administration Server that the node that they are installing on is the logical name of the cluster regardless of which physical machine is involved.
When running the Messaging Server Initial Runtime Configuration (see Creating the Initial Messaging Server Runtime Configuration) sure to specify the fully-qualified HA logical host name of the cluster of Messaging Server.
Configure Messaging Server using the cluster host name. If you do otherwise, then you’ll need to re-configure a second time using the cluster host name.