Monitoring
Monitoring is another X-Pack component that has grown out of the requirement of having a UI to monitor the cluster, indices, and nodes present in Elasticsearch. It provides us with detailed statistics for each cluster, each of the indices present in the cluster, and for each of the nodes.
By making Monitoring incorporated in X-Pack, now you can access the Monitoring UI directly from Kibana, thereby eliminating the need to leave Kibana. Earlier, it was known as Marvel, which provided you with a UI to monitor and get statistics of clusters, nodes, and indices present in Elasticsearch. You can even see the performance of the Kibana instance that is running, which is an addition.
Monitoring consists of two sub-components: a monitoring agent and a monitoring application. The monitoring agent is to be installed on every node from which you want to fetch statistics, and collects the data and indices of the data in Elasticsearch on which data is visualized using the Monitoring dashboards...