On Wed, Apr 4, 2012 at 8:04 AM, aaron morton <aaron@thelastpickle.com> wrote:
It depends on the workload. 

Increase the cache size until you see the hit rate decrease, or see it create memory pressure. Watch the logs for messages that the caches have been decreased. 

Take a look at the Recent Read Latency for the CF. This is how long it takes to actually read data on that node. You can then work out the throughput taking into account the concurrent_readers setting in the yaml. 

Thanks Aaron, I will try this.