A High Availability (HA) Controller deployment helps you minimize the disruption caused by a server or network failure, administrative downtime, or other interruptions. An HA deployment is made up of two Controllers, one in the role of the primary and the other as the secondary.

The Enterprise Console automates the configuration and administration tasks associated with a highly available deployment on Linux systems. Controller HA pairs are not available on Windows Enterprise Console machines.

Essentially, to set up high availability for Controllers, you are configuring master-master replication between the MySQL instances on the primary and secondary Controllers.

An important operational point to note is that while the databases for both Controllers should be running, both Controller application servers should never be active (i.e., running and accessible by the network) at the same time. Similarly, the traffic distribution policy you configure at the load balancer for the Controller pair should only send traffic to one of the Controllers at a time (i.e., do not use round-robin or similar routing distribution policy at the load balancer).