ElasticSearch return 4 primary shards instead of 3

Question

I created an index with 3 primarys shards but ElasticSearch return and indicate that there are 4 primary shards.

# Deleting the data in the cluster
DELETE /_all

# Create an index with 3 primary shards with 1 replica each
PUT /blogs
{
   "settings" : {
      "number_of_shards" : 3,
      "number_of_replicas" : 1
   }
}

# Retrieve the cluster health
GET /_cluster/health

And here is the response :

{
   "cluster_name": "clus",
   "status": "yellow",
   "timed_out": false,
   "number_of_nodes": 1,
   "number_of_data_nodes": 1,
   "active_primary_shards": 4,
   "active_shards": 4,
   "relocating_shards": 0,
   "initializing_shards": 0,
   "unassigned_shards": 4
}

I thought that there was only the number of replica shards that could change and that the number of primary shards was fixed at the time that the index was created, where does come from the fourth primary shard ?

Alcanzar Alcanzar · Accepted Answer · 2014-08-28T16:28:45

Since your example shows thing in marvel syntax, I assume you are using marvel. It will create an index for it's own data (so that's the 4th shard you are seeing). Try GET /_cat/shards to see this.

ElasticSearch return 4 primary shards instead of 3

1 Answers