Before you begin reading this guide, we recommend you try running the 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 ” expected mapper parsing failures. got ” 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: replication.
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).
Overview
Replication refers to storing a redundant copy of the data. Starting from version 7.x, Elasticsearch creates one primary shard with a replication factor set to 1. Replicas never get assigned to the same node on which primary shards are assigned, which means you should have at least two nodes in the cluster to assign the replicas. If a primary shard goes down, the replica automatically acts as a primary shard.
What it is used for
Replicas are used to provide high availability and failover. A higher number of replicas is also helpful for faster searches.
Examples
Update replica count
PUT /api-logs/_settings?pretty
{
"index" : {
"number_of_replicas" : 2
}
}Common problems
- By default, new replicas are not assigned to nodes with more than 85% disk usage. Instead, Elasticsearch throws a warning.
- Creating too many replicas may cause a problem if there are not enough resources available in the cluster.
Log Context
Log”expected mapper parsing failures. got”classname is TransportWriteAction.java We extracted the following from Elasticsearch source code for those seeking an in-depth context :
final Location currentLocation) throws Exception {
final Location location;
if (operationResult.getFailure() != null) {
// check if any transient write operation failures should be bubbled up
Exception failure = operationResult.getFailure();
assert failure instanceof MapperParsingException : "expected mapper parsing failures. got " + failure;
throw failure;
} else {
location = locationToSync(currentLocation; operationResult.getTranslogLocation());
}
return location;Run the Check-Up to get customized recommendations like this:
Run Check-Up
Heavy merges detected in specific nodes
Description
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 recommendation]