> On Mar 5, 2018, at 6:52 AM, D. Salvatore <dd.salvat...@gmail.com> wrote:
>
> Hello everyone,
> I am benchmarking a Cassandra installation on Azure composed of 4 nodes
> (Standard_D2S_V3 - 2vCPU and 8GB ram) with a replication factor of 2.
Bit smaller than most people would want to run in production.
> To benchmark this testbed, I am using a single YCSB instance with the
> workload C (100% read request), a Consistency level ONE and only 10 clients (
> so very low load).
Be sure that you understand the difference between your benchmark and your prod
use case - especially differences in data model and consistency levels.
>
> However, I founded that the average latency gathered by YCSB is much
> different from the one obtained from the JMX
> (org.apache.cassandra.metrics:type=ClientRequest,scope=Read,name=Latency)
> I ran the workload for over an hour and:
> - YCSB returns around 4000 us as average latency
> - JMX returns around 780 us as average latency
>
> It is a quite an important difference in performance that I don't know how to
> justify.
> Do you have any idea from where this difference comes from?
Could be app side pauses (ycsb being java itself, could be seeing jvm gc on the
load testing servers)
>
> Regarding the throughput, the value is the same across both the reading
> (~2400ops/sec)
>
> Thank in advance
> Salvatore
>
