I have a 5-node Cassandra cluster. Each node has disk space of 5TB. The real usage for each node is around 2.5TB depending on allocations and compactions (some are around 2TB some around 2.8).
I would like to add new nodes to the cluster with lower disk space (2TB for example).
How can I be sure that the new nodes will have enough disk space when Cassandra will redistribute data? How can I be sure that my new nodes are not too small?
I'm afraid that 2TB won't be enough, but what about 2.5TB?