Learn what to do if the Elasticsearch node is disconnected. Our Server Management Support team is here to help you with your questions and concerns.

Elasticsearch node disconnected | Cause & Fixes

Elasticsearch is a popular distributed search and analytics engine. It stores and retrieves data in a distributed manner. Furthermore, it consists of a cluster of one or more nodes working together to offer reliable and fast search results.

However, when a node in the Elasticsearch cluster disconnects, it is no longer able to communicate with the rest of the cluster. This may be due to several reasons, like network issues, hardware failures, or software errors.

Furthermore, a disconnected node leads to a number of problems for the Elasticsearch cluster. For instance, queries may fail, data may become inconsistent, and cluster health may be compromised.

We can diagnose whether a node has been disconnected or not by looking at:

• Monitoring data
• Elasticsearch logs

Some of the root causes behind a node getting disconnected include:

• Excessive garbage collection from JVM

  If the JVM heap does not follow a regular sawtooth pattern and shows an irregular curve upwards instead, it can cause the node to get disconnected.

  We may also come across logs similar to the one below:

  [2023-04-10T19:43:27,628][WARNING][o.e.m.j.JvmGcMonitorService] [ES2-QUERY] [gc][550567] overhead, spent [615ms] collecting in the last [1s]

  In this scenario, it is clear the JVM garbage collection issue is behind the node getting disconnected.
• Configuration issues

  According to our experts, configuration issues often appear immediately when a node is started or restarted. Furthermore, it may also occur when nodes are removed or added from the cluster. Interestingly, certain configuration issues arise only when the cluster is under stress.

  For example, excessive garbage collection, or loss of a node.

How to prevent node disconnection

• Increase the value of the discovery.zen.ping_timeout setting
• Check network connectivity
• Check the firewall settings
• Increase the heap size
• Monitor the cluster health
• Keep Elasticsearch up-to-date

Let us know in the comments if you need further help with a disconnected node in Elasticsearch.

[Need assistance with a different issue? Our team is available 24/7.]

Conclusion

In summary, our Support Techs demonstrated what to do if an Elasticsearch node is disconnected.