I have a testing cluster with: A (dc1), B (dc1), C(dc2), D(dc2). The replication factor is 2 so I assume each DC will have a complete copy of the data. Also I'm using PropertyFileEndPointSnitch with rack.properties for the dc and rack settings.

So, what's the steps to add another datacenter and increase replication factor to 3 to ensure that dc3 will also get a complete copy of the data? Meaning each of these 3 dc will have a complete copy of the data and they keep synchronize with each other with new changes. What I'm guessing is:

1) Increase replication factor of A/B/C/D to 3, modify their rack.properties to include E(dc3) and F(dc3) then restart them one by one. At this point E and F haven't been started yet.
2) Bootstrap E and F (both from dc3) to join the cluster.

in this case, will cassandra automatically put the 3rd replica to E and F?


 P.S here what the cassandra document says about dc replication but I'm not sure what will happen when you join nodes from the 3rd dc.