Master Node Configuration for Atlas Clusters
The master node configuration in itself is rather simple. First, you must choose which appliance will serve as the master node. Unless the deployment is for a small number of representatives, the master node will ideally be a B400 appliance. A second, matching backup will need to be used for the pairing of the master role in a failover relationship.
Since the master node will play a role in every support session, the network in which that master node resides should be a central location in relation to your network as a whole.
Once you have planned where your master node will reside physically, the next step is to confirm the name of your support site. This hostname will serve as the central hub, essentially, where your customers will come seeking support (e.g., http://support.example.com). You will also need to have a canonical hostname registered in your DNS environment for each appliance in the cluster.
The master node will also have the capacity to handle support sessions just as does a traffic node. If there are network or environmental conditions disrupting the availability of a traffic node (from a client’s point-of-view) then a support session can fall back to the master appliance. In this scenario, the master appliance will handle all aspects of the session without utilizing a traffic node. An administrator can set how many concurrent sessions can fall back to the master appliance at any given time.