When expanding a cluster, do all the new nodes need to be added to the heartbeat subcontext of the network context in the configuration files of all existing nodes? Do they all need to be added to the seed node list of all client applications? Do they need to be added to the dc subcontext of the xdr context in the configuration files of all nodes of all clusters that ship to the expanded cluster?
Answer
In a word, no. Seed nodes, whether for heartbeat within a cluster, clients connecting to a cluster, or XDR connecting to another cluster, are checked in the order they're seen in the configuration until one responds, and then that node provides the cluster membership and partition map. Nodes after that are not queried for cluster information. For resilience, we recommend listing several seed nodes, but in normal circumstances, only one is needed.
