When setting up a log analytics system, it is extremely important to define your data retention policy as Elasticsearch can't hold all the data that you have, which may result in data loss. There should be a process to automatically delete old indices after a certain defined period.

The Elasticsearch Curator (https://github.com/elasticsearch/curator) is especially useful to manage your indices. You can schedule Curator to delete old indices based on your need. For example, the following command can be set up in a crontab to delete indices older than 10 days at a specified time, daily:

curator --host 10.0.0.7 delete indices --older-than 10 --time-unit days  --timestring '%Y.%m.%d'