# ES 6.1.2 Cluster shows performance bottleneck

**URL:** <https://discuss.elastic.co/t/es-6-1-2-cluster-shows-performance-bottleneck/153208>\
**Category:** Elasticsearch\
**Tags:** rally\
**Created:** [October 19, 2018, 5:47pm UTC](https://discuss.elastic.co/t/es-6-1-2-cluster-shows-performance-bottleneck/153208 "2018-10-19T17:47:18Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![dliappis](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dliappis/32/56174_2.png) [@dliappis](https://discuss.elastic.co/u/dliappis)\
**Post date:** [October 22, 2018, 9:09am UTC](https://discuss.elastic.co/t/es-6-1-2-cluster-shows-performance-bottleneck/153208/2 "2018-10-22T09:09:16Z")

</div>

Hello,

I don't know if you checked already for comparison, but we have an archive of release benchmarks in the usual page ([https://elasticsearch-benchmarks.elastic.co](https://elasticsearch-benchmarks.elastic.co)) on our bare metal environment; in particular looking at the 99th percentile service\_time for the `geonames` track between `2.4.6` and `6.4.0` on 1node our own benchmarks show:

`scroll` service time is less on `6.4.0`: `666.008ms` vs `751.116ms` on `2.4.6`.  
`country_agg_cached` is basically the same (`3.796`ms vs `3.783`ms)  
`country_agg_uncached` service time is a bit slower in 6.4 (and 5.6) giving `222.651ms` compared to `190.085ms` on `2.4.6` in service time, but nowhere near the 115% increase you are observing.

The first observation is that since your latency is \>\> service\_time in your 6.1.2 Elasticsearch (and this is not observed in the 2.4 setup), the cluster is bottlenecked somewhere (see also [here](https://discuss.elastic.co/t/why-the-percentile-latency-is-several-times-more-than-service-time/69630)).

My first thought would be to check if the environment setup is precisely the same (in terms of h/w) between your 2.4 and 6.1 cluster; e.g. are you using exactly the same instance types for ES nodes and in the same region and availability zone as well?

In addition to that, is the operating system the same (inc. version) for both environments? Apart from differences arising from different kernels and settings, the `i3.2xlarge` instance you are using for the data node benefits from NVMe instance store, however, this can not be efficiently utilized in older Linux kernels.

You mentioned you checked the system metrics, have you in particular looked at io metrics (`iostat -xz 1`)? I am linking here a useful [performance checklist](http://www.brendangregg.com/blog/2016-05-04/srecon2016-perf-checklists-for-sres.html) written by Brendan Gregg for checking resource utilization.

Dimitris

---

_[View the full topic](https://discuss.elastic.co/t/es-6-1-2-cluster-shows-performance-bottleneck/153208)._