Elasticsearch - Locking Memory for Production

A common error people face when putting an Elasticsearch cluster to production has to do with memory locking. Tipically users would see errors like “Unable to lock JVM memory (ENOMEM). This can result in part of the JVM being swapped out. Increase RLIMIT_MEMLOCK (ulimit)” or “memory locking requested for elasticsearch process but memory is not locked”.

Here is what I have done to lock the memory on Elasticsearch nodes. This procedure will work in any distribution that use systemd.

1) Override the elasticsearch service

systemctl edit elasticsearch

Then add the following and save:

[Service]
LimitMEMLOCK=infinity

2) Check the elasticsearch.yml file

Make sure your elasticsearch.yml has the following config:

bootstrap.memory_lock: true

3) Reload the service and start Elasticsearch

systemctl daemon-reload
service elasticsearch restart

Thats it, the RAM should now be locked. Its also a good idea to disable swap