Before you begin reading this guide, we recommend you run Elasticsearch Error Check-Up which analyzes 2 JSON files to detect many errors.
To easily locate the root cause and resolve this issue try AutoOps for Elasticsearch & OpenSearch. It diagnoses problems by analyzing hundreds of metrics collected by a lightweight agent and offers guidance for resolving them.
This guide will help you check for common problems that cause the log ” Updating number-of-replicas to for indices ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: cluster, indices, metadata and settings.
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) {
