Shared Elasticsearch cluster
In case you have a large shared Elasticsearch cluster that you want to operate multiple Optimize instances on that are intended to run in complete isolation from each other, it is required to change the es.settings.index.prefix setting for each Optimize instance.
Although a shared Elasticsearch cluster setup is possible, it's recommended to operate a dedicated Elasticsearch cluster per Optimize instance.
This is due to the fact that a dedicated cluster provides the highest reliability (no resource sharing and no breaking side effects due to misconfiguration) and flexibility (e.g. Elasticsearch and/or Optimize updates can be performed independently between different Optimize setups).
The following illustration demonstrates this use case with two Optimize instances that connect to the same Elasticsearch cluster but are configured with different es.settings.index.prefix values. This results in different indexes and aliases created on the cluster, strictly isolating the data of both Optimize instances, so no instance accesses the data of the other instance.
Changing the value of es.settings.index.prefix after an instance was already running results in new indexes being created with the new prefix value. There is no support in migrating data between indexes based on different prefixes.
