Provisioning several db processes on the same cluster

For cluster deployments, every installation consists of 2 or more instances. In case of Cassandra or MongoDB, the only way to test all aspects of selected topology, cluster configuration is to spin up such cluster and work with it.
The single instance doesn't give the behavior of specific cluster topology.

From other hand it is common use case the database for development, testing purposes without huge load and no reason to provide dedicated resources.

So, in order to increase resource utilization and keep isolation between clients it is suggested to share the same infrastructure between databases.

For mongo and cassandra it can be separate daemons

The idea is still under discussion.