Elasticsearch Loaded Cluster Managers in OpenSearch

By Opster Team

Updated: Apr 11, 2023

| 1 min read

In addition to reading this guide, we recommend you run the Elasticsearch Health Check-Up. It will detect issues and improve your Elasticsearch performance by analyzing your shard sizes, threadpools, memory, snapshots, disk watermarks and more.

The Elasticsearch Check-Up is free and requires no installation.

Before you begin reading this guide, we recommend you try running the OpenSearch Error Check-Up which analyzes 2 JSON files to detect many configuration errors.

Loaded cluster managers is another one of the issues that can be prevented and resolved automatically using AutoOps for OpenSearch. AutoOps will also help you optimize other important settings and processes to improve performance and ensure high availability for your crucial data. Try AutoOps for free.


Sometimes you can observe that the CPU and load on one of your cluster_manager is higher than on others.

This is absolutely normal behavior assuming that the loaded cluster manager is the elected master. Although you need more than one cluster manager (and ideally an odd number), only one of these nodes will be active at any one time. If CPU is very high and the node appears to be overloaded, then this may be cause for concern, since an overloaded cluster manager may cause instability in the cluster.

How to resolve it

How to fix loaded cluster_manager in OpenSearch

  1. Check for split brain

    Make sure you are not suffering from the split brain problem described.

  2. Check other processes

    Ensure that there are no other processes running on the cluster manager which could cause it to become unstable. 

  3. Check the cluster manager logs

    Check the loaded cluster manager logs. If the elected cluster manager is loaded, the log can reveal the potential causes, such as: high rate of mapping exceptions, too many doc types (for ES versions older than v6), or large metadata – too many fields/indices/shards.

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