The version of Elasticsearch supported for the Sentinel version 8.5.1.0 is 7.10.2-OSS. To upgrade a Sentinel cluster with external Elasticsearch nodes to 8.5.1.0 you must upgrade the external nodes to the supported version of Elasticsearch.
After you delete the previous version of Elasticsearch, search for the existence of the Elasticsearch data and configurations in the node. Delete all these data and configurations. Once done, you can continue the installation of the Elasticsearch 7.10.2-OSS rpm. Ensure that the elasticsearch.yml files are updated with the node information.
Stop the external nodes before the upgrade and uninstall the current Elasticsearch version. Delete the data and configurations for the previous version on each external node and install the supported version (7.10.2-OSS). For more information, see Installing Elasticsearch.
Do not start these nodes before the sentinel node comes up after the upgrade.
If you wish to save any custom dashboards and visualizations that you might have created in Kibana, export them from Kibana and import them back to Kibana after the upgrade.
NOTE:After upgrading to 8.5.1.0, the new Elasticsearch will not have any older data. If you want to migrate the older data to Elasticsearch you can do it using the data uploader tool. It can be done after the connection between all the nodes is made and both Elasticsearch and Kibana are running. For more information, see the Section 36.0, Migrating Data.