|Using OpsCenter / Cluster administration|
Cluster rebalancing is a process that makes sure each node in a Cassandra cluster is managing an equal amount of data.
Currently, OpsCenter only supports rebalancing on clusters using the random partitioner or murmur 3 partitioner. Ordered partitioners are not supported. When using the random partitioner or murmur 3 partitioner, a rebalance is usually required only when you have changed the cluster topology in some way, such as adding or removing nodes or changing the replica placement strategy.
A cluster is considered balanced when each node is responsible for an equal range of data. This is done by evaluating the partitioner tokens assigned to each node to make sure that the data ranges each node is responsible for are even. Even though a cluster is considered balanced, it is still possible that one or more nodes have more data than the others. This is because the size of the rows is not taken into account, only the number of rows managed by each node.