title: Unassigned Shards in Cluster
body: <p>I have an ES cluster which is playing up. At one point I had all primary and replica shards correctly assigned to 4 of my 5 nodes, but in trying to get some onto the 5th node I have once again lost my replica shards. Now my primary shards exist only on 3 nodes. </p>
  
  <p>I am trying to get to the bottom of the issue:</p>
  
  <p>On trying a forced allocation such as:</p>
  
  <pre><code>{
    "commands": [
      {
        "allocate": {
          "index": "group7to11poc",
          "shard": 7,
          "node": "SPOCNODE1"
        }
      }
    ]
  }
  </code></pre>
  
  <p>I get the following response. I am having trouble finding out the exact problem!</p>
  
  <pre><code>explanations: [1]
    0:  {
      command: "allocate"
      parameters: {
      index: "group7to11poc"
      shard: 7
      node: "SPOCNODE5"
      allow_primary: true
    }-
  decisions: [11]
    0:  {
      decider: "same_shard"
      decision: "YES"
      explanation: "shard is not allocated to same node or host"
    }-
    1:  {
      decider: "filter"
      decision: "NO"
      explanation: "node does not match index include filters [_id:"4rZYPBOGRMK4y9YG6p7E2w"]"
    }-
    2:  {
      decider: "replica_after_primary_active"
      decision: "YES"
      explanation: "primary is already active"
    }-
    3:  {
      decider: "throttling"
      decision: "YES"
      explanation: "below shard recovery limit of [2]"
    }-
    4:  {
      decider: "enable"
      decision: "YES"
      explanation: "allocation disabling is ignored"
    }-
    5:  {
      decider: "disable"
      decision: "YES"
      explanation: "allocation disabling is ignored"
    }-
    6:  {
      decider: "awareness"
      decision: "YES"
      explanation: "no allocation awareness enabled"
    }-
    7:  {
      decider: "shards_limit"
      decision: "YES"
      explanation: "total shard limit disabled: [-1] &lt;= 0"
    }-
    8:  {
      decider: "node_version"
      decision: "YES"
      explanation: "target node version [1.3.2] is same or newer than source node version [1.3.2]"
    }-
    9:  {
      decider: "disk_threshold"
      decision: "YES"
      explanation: "disk usages unavailable"
    }-
    10:  {
      decider: "snapshot_in_progress"
      decision: "YES"
      explanation: "shard not primary or relocation disabled"
    }-
  </code></pre>