TODO: Describe how YCSB is poor for putting up a decent cluster load.
TODO: Describe setup of YCSB for HBase. In particular, presplit your tables before you start a run. See HBASE-4163 Create Split Strategy for YCSB Benchmark for why and a little shell command for how to do it.
Ted Dunning redid YCSB so it's mavenized and added facility for verifying workloads. See Ted Dunning's YCSB.