Normally, automatic media server failover is configured before the original media server fails.
On UNIX and Linux systems, when you configure this option, it sets the FAILOVER_RESTORE_MEDIA_SERVERS parameter in the bp.conf file.
To enable automatic failover to an alternate server
In the NetBackup Administration Console , open the Restore Failover host properties for the master server.
Add an entry in the Alternate Restore Failover Machines list; name the media server and failover restore server(s).
Stop and restart the NetBackup Request Manager daemon or service on the master server.