...
By default, MB is packaged with all three components. In a clustered setup, it is possible to have these three components separately and shared with each other. This separation introduces several possible deployment scenarios that can be customized according to your requirement.
The deployment pattern of deploying WSO2 Message Broker with external Cassandra Cluster and external ZooKeeper cluster is the production recommendation for WSO2 Message Broker clustered deployment. This deployment pattern provides the flexibility of going for any number of Cassandra nodes, MB nodes and ZooKeeper nodes and it makes it easy to isolate the issues if there are any.
To enable the governance registry to be used across all nodes, you must share the registry. For details, see Sharing the Governance Registry Across the MB Cluster.
...