What's the easy way to create a cluster with 2 nodes on the same machine?

Question

I'm testing Elasticsearch and I'm trying to create a simple cluster with 2 nodes on a single machine (on Fedora)

I'm launching a first instance named Node1:

sudo bin/elasticsearch -Des.node.name=Node1 -Des.http.port=9200

And a second instance named Node2 in another terminal:

sudo bin/elasticsearch -Des.node.name=Node2 -Des.http.port=9201

The console output is the following for both commands:

log4j:WARN No appenders could be found for logger (node).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

GET http://127.0.0.1:9200 gives me:

{
  "status" : 200,
  "name" : "Node1",
  "version" : {
    "number" : "1.1.1",
    "build_hash" : "f1585f096d3f3985e73456debdc1a0745f512bbc",
    "build_timestamp" : "2014-04-16T14:27:12Z",
    "build_snapshot" : false,
    "lucene_version" : "4.7"
  },
  "tagline" : "You Know, for Search"
}

and GET http://127.0.0.1:9201 gives me

{
  "status" : 200,
  "name" : "Node2",
  "version" : {
    "number" : "1.1.1",
    "build_hash" : "f1585f096d3f3985e73456debdc1a0745f512bbc",
    "build_timestamp" : "2014-04-16T14:27:12Z",
    "build_snapshot" : false,
    "lucene_version" : "4.7"
  },
  "tagline" : "You Know, for Search"
}

That looks good but now if I get the cluster health I have different results on 9200 and 9201:

GET http://127.0.0.1:9200/_cluster/health?pretty=true

{
  "cluster_name" : "elasticsearch",
  "status" : "yellow",
  "timed_out" : false,
  "number_of_nodes" : 1,
  "number_of_data_nodes" : 1,
  "active_primary_shards" : 6,
  "active_shards" : 6,
  "relocating_shards" : 0,
  "initializing_shards" : 0,
  "unassigned_shards" : 6
}

GET http://127.0.0.1:9201/_cluster/health?pretty=true

{
  "cluster_name" : "elasticsearch",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 1,
  "number_of_data_nodes" : 1,
  "active_primary_shards" : 0,
  "active_shards" : 0,
  "relocating_shards" : 0,
  "initializing_shards" : 0,
  "unassigned_shards" : 0
}

Why do I have only 1 node on the same cluster? Why is it green and also yellow? Looks like the cluster is not working...

How do I make this works? Where are the Zen Discovery logs?

Related questions:

Can you start two nodes minus your additional settings and they discover each other? — Nathan Smith
Two times sudo bin/elasticsearch without any settings gives me the same result.. (with autogenerated node names and port) — Yves M.
Looks like the two nodes cannot properly communicate, I'd look for firewalls or similar. They are effectively forming two different clusters with same name. Maybe they are using two different devices? — javanna

Paige Cook Paige Cook · Accepted Answer · 2014-05-06T17:43:55

Elasticsearch nodes cannot share the same data directory. So you need to add an additional parameter: -Des.data.path=/path/to/data

 sudo bin/elasticsearch -Des.node.name=Node1 -Des.http.port=9200 
   -Des.data.path=/path/to/data1

 sudo bin/elasticsearch -Des.node.name=Node2 -Des.http.port=9201 
   -Des.data.path=/path/to/data2

That should work for you. Also, note that in this case you do not need to specify the port numbers as Elasticsearch will automatically grab the next available free port, starting with 9200 by default.

What's the easy way to create a cluster with 2 nodes on the same machine?

3 Answers