Do note that, if existing keyspaces are defined using SimpleStrategy, queries running at LOCAL consistency levels (mainly LOCAL_QUORUM) could begin to fail. The Simple replication strategy is not data center-aware, so queries could be directed to the new nodes before they have data. This behavior is the main failing of SimpleStrategy.
To get data to the nodes in the new data center, we'll need to first modify the keyspace(s) to allow replication to them, as follows:
ALTER KEYSPACE packt WITH replication = {'class': 'NetworkTopologyStrategy', 'ClockworkAngels': '3', 'VaporTrails': '3'};
Remember, you will also need to adjust replication for the system_auth, system_distributed, and system_traces keyspaces as well. ...
