Apache Cassandra Maintenance and Repair

In Apache Cassandra, when using "nodetool repair", it is crucial to think in terms of token ranges rather than individual tokens. The default options for "nodetool repair" initiate a repair for every token range owned by the node. However, using the "-pr" option allows each node to pick a subset of its token range for repair, ensuring that every token range is only repaired once across all nodes in the cluster. This becomes especially important when dealing with multiple data centers and large numbers of nodes. Additionally, Cassandra 2.1 introduced incremental repair, which further optimizes the repair process by only performing synchronization on previously unrepaired data.