title: ElasticSearch issue when adding new path.data
body: <p>I'm running a two nodes cluster Elasticsearch, 1 master + 1 node. Everything is running smoothly and all the indices are green, up and running (though no replica right now).</p>
  
  <p>My current elasticsearch configuration is:</p>
  
  <pre><code>path.data = /path/to/data
  </code></pre>
  
  <p>However I wanted to add an additional path (LVM volume) to expand Elasticsearch's disk size. I did shut down the ES data node, then I changed the elasticsearch.yml conf file as follows:</p>
  
  <pre><code>path.data = ["/path/to/data", "/path/to/newdata"]
  </code></pre>
  
  <p>And I restarted the data node. The cluster immediately turned red with all the shards unassigned. I also checked the global disable allocation setting and it's:</p>
  
  <pre><code>routing.allocation.disable_allocation: false
  </code></pre>
  
  <p>I shut down again the node, removed the second path, restarted the cluster and everything went green again. Note that ElasticSearch correctly detected the new data path and indeed the disk space was the increased one. </p>
  
  <p>How can I add a second path to the ES data node to increase disk space and having ElasticSearch correctly recognizing it?</p>
  
  <p>Many thanks in advance for your help!</p>
  
  <p>**** Added ****</p>
  
  <p>Elasticsearch build 1.7.3</p>
  
  <p>_nodes/stats (BEFORE)</p>
  
  <pre><code>     "fs": {
          "timestamp": 1445875849977,
          "total": {
             "total_in_bytes": 50647003136,
             "free_in_bytes": 39121285120,
             "available_in_bytes": 36850778112,
             "disk_reads": 6555,
             "disk_writes": 3959,
             "disk_io_op": 10514,
             "disk_read_size_in_bytes": 117785600,
             "disk_write_size_in_bytes": 34197504,
             "disk_io_size_in_bytes": 151983104,
             "disk_queue": "0",
             "disk_service_time": "0"
          },
          "data": [
             {
                "path": "/data/cluster-name/nodes/0",
                "mount": "/",
                "dev": "/dev/sda1",
                "type": "ext4",
                "total_in_bytes": 50647003136,
                "free_in_bytes": 39121285120,
                "available_in_bytes": 36850778112,
                "disk_reads": 6555,
                "disk_writes": 3959,
                "disk_io_op": 10514,
                "disk_read_size_in_bytes": 117785600,
                "disk_write_size_in_bytes": 34197504,
                "disk_io_size_in_bytes": 151983104,
                "disk_queue": "0",
                "disk_service_time": "0"
             }
          ]
       },
  </code></pre>
  
  <p>_nodes/stats (AFTER)</p>
  
  <pre><code>"fs": {
          "timestamp": 1445876141872,
          "total": {
             "total_in_bytes": 940360904704,
             "free_in_bytes": 649207984128,
             "available_in_bytes": 626626637824,
             "disk_reads": 8840,
             "disk_writes": 246,
             "disk_io_op": 9086,
             "disk_read_size_in_bytes": 127649792,
             "disk_write_size_in_bytes": 13971456,
             "disk_io_size_in_bytes": 141621248,
             "disk_queue": "0",
             "disk_service_time": "0"
          },
          "data": [
             {
                "path": "/data/cluster-name/nodes/0",
                "mount": "/",
                "dev": "/dev/vda1",
                "type": "ext4",
                "total_in_bytes": 422616936448,
                "free_in_bytes": 131537268736,
                "available_in_bytes": 114234032128,
                "disk_reads": 8524,
                "disk_writes": 232,
                "disk_io_op": 8756,
                "disk_read_size_in_bytes": 126358528,
                "disk_write_size_in_bytes": 13914112,
                "disk_io_size_in_bytes": 140272640,
                "disk_queue": "0",
                "disk_service_time": "0"
             },
             {
                "path": "/data-new/cluster-name/nodes/0",
                "mount": "/data-new",
                "dev": "/dev/mapper/vg0-lvol0",
                "type": "ext4",
                "total_in_bytes": 517743968256,
                "free_in_bytes": 517670715392,
                "available_in_bytes": 512392605696,
                "disk_reads": 316,
                "disk_writes": 14,
                "disk_io_op": 330,
                "disk_read_size_in_bytes": 1291264,
                "disk_write_size_in_bytes": 57344,
                "disk_io_size_in_bytes": 1348608
             }
          ]
       },
  </code></pre>