Adding more nodes to Cassandra (scaling up) or shrinking the number of nodes (scaling down) is a pretty straightforward task. In a smaller and moderate-sized Cassandra cluster setup (say, fewer than 25 nodes), it can be easily managed by doing the tasks manually. But in larger clusters, the whole process can be automated by writing appropriate shell script to perform the task.
Cassandra is one of the purest distributed systems where all the nodes are identical. So, adding a new node is just a matter of launching a Cassandra service with almost the same parameters as any other machine in the ring. In a cloud environment such as Amazon Web Services, it is a pretty common practice to have a machine image of Cassandra that contains the blueprint of a Cassandra node. Each time you have to add a node to the cluster, you launch the AMI, tweak a couple of parameters that are specific to the node, and done. It is as simple as that.
To add a new node to the cluster,...