Hello guys! I was reading about https://cassandra.apache.org/doc/latest/architecture/dynamo.html#networktopologystrategy I would like to understand a concept related to the node load balancing. I found a cluster with vnodes = 256 replication factor = 3 and 2 racks. This is unbalanced because the racks are not a multiplier of the replication factor. However, my plan is to move all the nodes in a single rack to eventually scale up and down the node in the cluster once at the time. If I had 3 racks and I would like to keep the things balanced I should scale up 3 nodes at the time one for each rack.
If I would have 3 racks, should I have also 3 different datacenters so one datacenter for each rack? Can I have 2 datacenters and 3 racks?
If this is possible one datacenter would have more nodes than the others? Could it be a problem?
I am thinking to split my cluster in one datacenter for reads and one for writes and keep all the nodes in the same rack so I can scale up once node at the time.
Please correct me if I am wrong