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Elasticsearch is a distributed search server based on Apache Lucene, which acts as the application’s search and analytic engine. Some solutions to common problems with Elasticsearch and AtoM are below.

Disable auto-discovery

To prevent Elasticsearch from auto-discovering other nodes on the network, add the following to /etc/elasticsearch/config/elasticsearch.yml

node.local: true # disable network

Check cluster health


curl -XGET 'http://localhost:9200/_cluster/health?pretty=true'

Sample output:

  "cluster_name" : "testcluster",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 2,
  "number_of_data_nodes" : 2,
  "active_primary_shards" : 5,
  "active_shards" : 10,
  "relocating_shards" : 0,
  "initializing_shards" : 0,
  "unassigned_shards" : 0

Find problem shards

If the Cluster health returns as “red” or “yellow” you can find problem shards with:

curl -XGET 'http://localhost:9200/_cluster/health/?level=shards&pretty=true'

You can redirect the STDOUT to a text file and search for “red” or “yellow” to find the problem indexes/shards.

Cluster health is yellow

If Cluster health returns as yellow, it “means that the primary shard is allocated but replicas are not” [1]. This often means that you have do not have enough ES nodes in your cluster to support the desired number of replicas of an index. This happens when you have indexes with ‘number_of_replicas’ > (the number of ES nodes you are running - 1). For instance if you only have 1 ES node, number_of_replicas should be set to 0. To reduce (or increase) the number of replicas on an existing index, you can use:

curl -XPUT 'localhost:9200/my_index/_settings' -d '
    "index" : {
        "number_of_replicas" : 0

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