http://docs.datastax.com/en/archived/cassandra/2.2/cassandra/tools/toolsCStress.html?hl=stress
Simple read and write examples
$ cassandra-stress write n=1000000
Insert (write) one million rows.
$ cassandra-stress read n=200000
Read two hundred thousand rows.
$ cassandra-stress read duration=3m
Read rows for a duration of 3 minutes.
$ cassandra-stress read n=200000 no-warmup
Read 200,000 rows without a warmup of 50,000 rows first.