NSX Advanced Load Balancer can run with a single Controller (single-node deployment) or a three-node Controller cluster.
In a deployment that uses a single Controller, that Controller performs all administrative functions and all analytics data gathering and processing.
Adding two additional nodes to create a three-node cluster provides node-level redundancy for the Controller and maximizes performance for CPU-intensive analytics functions. Whereas the lone Controller in a single-node deployment performs all administrative functions and analytics data collection and processing, these tasks are distributed in three-node cluster.
In a three-node Controller cluster, one node is the primary (leader) node and performs the administrative functions. The other two nodes are followers (secondaries), and perform data collection for analytics, in addition to standing by as backups for the leader.
