NMS always runs on the Master server. There is a Slave server which is switched to Master server whenever there is a requirement. This is the redundancy feature available in the NMS. This can happen in two ways:
See also
Manage Servers
Understand set of operations for Managing Failover
Forced Switch from Master to Slave
Auto Switch from Master to Slave
Manual Switch from Slave to Master
Modify Hot-Standby Switchover Delay
