Elasticsearch + Debian 11 | tweak the server

Set ulimit -n:

Edit /etc/profile and add

ulimit -n 65535

Disable swapping by removing all swap lines from your fstab. As an alternative add the following line to your elasticsearch.yml:

bootstrap.memory_lock: true

Then test it using the famous Kibana (DevTools) Console:

GET _nodes?filter_path=**.mlockall

It should return true.

Do not tune the java dns timeouts.