Elasticsearch Cluster Administration

This series shares resources about running Elasticsearch clusters in production, such as configuration, troubleshooting, and cluster behavior understanding.

Slow Query Logs In Elasticsearch

Better understand the slow queries in Elasticsearch by using the slow logs. In this article, we discuss the log structure, the thresholds, and some potential root causes.

27 Nov 2021

Elasticsearch Settings

This article describes the different types of settings of Elasticsearch: cluster settings, index settings, node settings, the difference between static and dynamic settings, and some commonly used curl commands.

21 Aug 2021

How to prevent data loss in Elasticsearch?

Six practical solutions to improve data reliability: improve number of replicas, snapshot and restore, RAID, MQ, etc.

31 Jul 2021

Fix Corrupted Index in Elasticsearch

How to fix corrupted index in Elasticsearch cluster without snapshot?

14 Jul 2021

Disk Watermarks In Elasticsearch

Understanding different disk watermarks: low, high, and flood-stage in Elasticsearch. The symptom when the cluster reaches these values and how to mitigate or avoid the issues. Also, how to better operate your clusters using these watermarks.

10 Apr 2021

18 Allocation Deciders in Elasticsearch

This article explains the 18 allocation deciders in Elasticsearch: when they decide to allow, deny, or throttle the shard allocation under different circumstances. Also, a complete list of messages for unassigned shards.

27 Sep 2020

Elasticsearch: Common Index Exceptions

Explain the common Elasticsearch exceptions occurred when indexing new documents, with sample messages, analysis, suggestions and external resources for further investigation.

13 Sep 2020

GC in Elasticsearch

Basic information about garbage collection (GC) in Elasticsearch, including the default garbage collector used, JVM options, GC logging, and more.

30 Aug 2020

Discovery in Elasticsearch

How does discovery work in Elasticsearch? This article explains different mechanisms of discovery, the key settings, fault detection, related logs, and more.

22 Aug 2020