Sure, the benchmark website has an overview:
All benchmarks are run on bare-metal machines with the following specifications:
- CPU: Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz
- RAM: 32 GB
- OS: Linux kernel version 4.13.0-38
- OS TUNING:
- /sys/kernel/mm/transparent_hugepage/enabled = always
- /sys/kernel/mm/transparent_hugepage/defrag = always
- JVM: Oracle JDK 1.8.0_131-b11
If it's not the client node, the next thing I'd suspect is the test harness itself. You're trying to push about 100MB/s of data at the cluster, and it's possible that the test harness you've written just isn't fast enough to do this.
If the bottleneck is Elasticsearch then I'd expect to see tasks building up on the client node. You can see how busy the client node is by looking at things like
GET /_nodes/CLIENT-NODE-NAME/stats/thread_pool and
GET /_tasks?nodes=CLIENT-NODE-NAME. If the client node looks quiet then the bottleneck is outside the system.