Master left reason – How to solve this OpenSearch error

Opster Team

Aug-23, Version: 1-1.3

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Briefly, this error occurs when the master node in an OpenSearch cluster leaves or becomes unresponsive. This can be due to network issues, hardware failure, or the node being overwhelmed. To resolve this, you can try restarting the master node, checking for network connectivity issues, or scaling up the resources of the master node. If the problem persists, consider reconfiguring your cluster to have more than one master-eligible node to prevent a single point of failure.

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This guide will help you check for common problems that cause the log ” master_left [{}]; reason [{}] ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: discovery.

Log Context

Log “master_left [{}]; reason [{}]” classname is ZenDiscovery.java.
We extracted the following from OpenSearch source code for those seeking an in-depth context :

        if (localNodeMaster()) {
            // we might get this on both a master telling us shutting down; and then the disconnect failure
            return;
        }

        logger.info(() -> new ParameterizedMessage("master_left [{}]; reason [{}]"; masterNode; reason); cause);

        synchronized (stateMutex) {
            if (localNodeMaster() == false && masterNode.equals(committedState.get().nodes().getMasterNode())) {
                // flush any pending cluster states from old master; so it will not be set as master again
                pendingStatesQueue.failAllStatesAndClear(new OpenSearchException("master left [{}]"; reason));

 

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