Elasticsearch

Documentation

Configuration

• http://jprante.github.io/2012/11/28/Elasticsearch-Java-Virtual-Machine-settings-explained.html

Heap

• https://www.elastic.co/blog/a-heap-of-trouble

Garbage collection

• Garbage collect
• Garbage collection
• Elasticsearch Heap Size Usage and JVM Garbage Collection

Ideally:

• Young GC is processed quickly (within 50 ms).
• Young GC is not frequently executed (about 10 seconds).
• Old GC is processed quickly (within 1 second).
• Old GC is not frequently executed (once per 10 minutes or more).

HOWTO

Adjust log rotation

Is done in /etc/elasticsearch/log4j.properties

Number of logfiles to keep

appender.rolling.strategy.max 

Monitoring elasticsearch

Things to monitor

heap size

• node jvm.mem.heap_used_percent

garbage collection

Something like

node.jvm.uptime_in_millis/node.jvm.gc.collectors.young.collection_count

• How to monitor Elasticsearch performance
• Top 10 Elasticsearch Metrics to Monitor
• Performance metrics to monitor
• Heap Size Usage

Query the web interface

• 'cluster': 'http://localhost:9200/_cluster/stats',
• 'nodes'  : 'http://localhost:9200/_nodes/stats',
• 'indices': 'http://localhost:9200/_stats',
• 'health' : 'http://localhost:9200/_cluster/health'

Installing Elasticsearch

On Debian

deb https://artifacts.elastic.co/packages/oss-6.x/apt stable main

packages is called elasticsearch-oss now?

Terminology

shards

"blocks" of index data distributed over the nodes

Percolation

https://spinscale.de/posts/2021-09-15-understanding-elasticsearch-percolate-query.html

now throttling indexing for shard: segment writing can't keep up

• one doc about this

FAQ

Status is yellow

• Yellow cluster status explained

and look for unassigned shards

Update ingest-attachment

/usr/share/elasticsearch/bin/elasticsearch-plugin remove ingest-attachment
/usr/share/elasticsearch/bin/elasticsearch-plugin install ingest-attachment

Get version of active elasticsearch

wget -q -O - http://localhost:9200/_cluster/stats