The number of nodes in an HBase cluster may also be driven by required throughput for disk reads and/or writes. The throughput per node greatly depends on table cell size, data request patterns, as well as node and cluster configuration. Use YCSB tools to test the throughput of a single node or a cluster to determine if read/write throughput should drive your the number of nodes in your HBase cluster. A typical throughput for write operations for one region server is 5-15 Mb/s. Unfortunately, there is no good estimate for read throughput; it varies greatly depending on physical data size, request patterns, and hit rate for the block cache.
