About protecting against SAN media server failures
Unlike regular media servers, SAN media servers only protect themselves. A SAN media server connects directly to the backup storage in the same way as a regular media server. But it does not receive data from other client systems over a network or SAN link.
SAN media servers are usually deployed on the servers that support large, mission-critical applications, which are often clustered. While the application may be clustered, you do not need to cluster the SAN media server itself. Instead, install the SAN media server software on each member node of the cluster and create application cluster definitions in the NetBackup EMM database for each virtual name the cluster uses. Then create a storage unit using the virtual name of the cluster as the media server. The associated application with a given virtual name use the storage unit that is associated with the same virtual name for backups.