Updating number-of-replicas to for indices – How to solve related issues

Updating number-of-replicas to for indices – How to solve related issues

Opster Team

Feb-20, Version: 1.7-8.0


Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which can resolve issues that cause many errors.

This guide will help you check for common problems that cause the log ” Updating number-of-replicas to for indices ” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: cluster, indices, metadata and settings.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to pinpoint the cause of many errors and provides suitable actionable recommendations how to resolve them (free tool that requires no installation).

Log Context

Log “updating number_of_replicas to [{}] for indices {}” classname is MetaDataUpdateSettingsService.java
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                int updatedNumberOfReplicas = openSettings.getAsInt(IndexMetaData.SETTING_NUMBER_OF_REPLICAS; -1);
                if (updatedNumberOfReplicas != -1) {
                    routingTableBuilder.updateNumberOfReplicas(updatedNumberOfReplicas; actualIndices);
                    metaDataBuilder.updateNumberOfReplicas(updatedNumberOfReplicas; actualIndices);
                    logger.info("updating number_of_replicas to [{}] for indices {}"; updatedNumberOfReplicas; actualIndices);

                ClusterBlocks.Builder blocks = ClusterBlocks.builder().blocks(currentState.blocks());
                Boolean updatedReadOnly = openSettings.getAsBoolean(IndexMetaData.SETTING_READ_ONLY; null);
                if (updatedReadOnly != null) {


Run the Check-Up to get customized recommendations like this:

checklist Run Check-Up


Heavy merges detected in specific nodes



A large number of small shards can slow down searches and cause cluster instability. Some indices have shards that are too small…


Recommendations Based on your specific ES deployment you should…

Based on your specific ES deployment you should…


X-PUT curl -H [a customized code snippet to resolve the issue]




Optimize Elasticsearch Performance

Run The Tool