What is Cassandra's vnodes (virtual nodes)?

Vnodes (virtual nodes) are Cassandra's mechanism for distributing data and making cluster operations seamless. Each physical Cassandra node is responsible for multiple small token ranges (virtual nodes) rather than one large range. Default: 256 vnodes per node. Benefits: Automatic data distribution: when a new node joins or leaves, only small portions of data move — spread across many existing nodes rather than one neighbor taking all the burden. Simpler scaling: no manual token calculation needed when adding nodes. Better load balancing: more uniform distribution of token ranges. Faster recovery: when a node fails, the small vnodes it owned are distributed across many other nodes for faster streaming. Trade-offs: More compaction complexity: each node handles many token ranges. Network overhead: more inter-node communication. For large clusters, reduce vnodes from 256 to 16 or even 1 (one large token range) for better compaction and repair performance. The optimal vnode count depends on cluster size and workload.