When a verticle is deployed in High availability mode, it can fail over to any other nodes in the cluster started with the same HA group
The HA mode can be defined in a run or start command
A HA group defines a set of cluster.
It can be defined in a run or start command
There can be multiple HA groups in a cluster. Nodes will only failover to other nodes in the same group.
Defaults to 'DEFAULT'.