Couchbase Server Performance Drop

We are using couchbase DB with our products and we tested it under heavy load. The Database is performing well within first half an hour, after that performance is reduced.

Server (environment) details as follows,

  • OS : CentOS 6.7
  • RAM: 16GB
  • Disk : 80 Gb

Data Bucket details,

  • RAM : 7GB
  • Data RAM Quota : 8 GB
  • Index RAM Quota : 4 GB
  • SDK version : 2.2.6.RELEASE
  • Server Version: couchbase-server-enterprise-4.6.2-centos6.x86_64
    Databse server has only one node.

We applied OS level changes to the couchbase server node based on below article, still we were unable to get consistent performance.
Please guide us to identify the possible bottlenecks and get the database server into optimum performance.

Thank You.

Please look at below behavior of the couchbase server while it gets the traffic. We suspects the reason behind the performance fluctuation is, due to drop of ops per second. Server does not consumed CPU and RAM at that time as well. Can you please give us possible reasons behind this behavior?