在你的系统上试试cassandra压力测试，根据输出你可以计算出硬件需求。单个节点的输出示例：

Cassandra Performance on 1 Node Cluster Write operation:

Results:
op rate                   : 6636
partition rate            : 6636
row rate                  : 6636
latency mean              : 30.1
latency median            : 25.9
latency 95th percentile   : 65.6
latency 99th percentile   : 94.3
latency 99.9th percentile : 140.9
latency max               : 1381.2
total gc count            : 150
total gc mb               : 22123
total gc time (s)         : 8
avg gc time(ms)           : 51
stdev gc time(ms)         : 12
Total operation time      : 00:02:30
END