title: Elasticsearch shard relocation not working
body: <p>I added 12 new data nodes to an existing cluster of 8 data nodes.  I am trying to shutdown the previous 8 nodes using the "exclude allocation" as recommended</p>
  
  <blockquote>
    <p>curl -XPUT localhost:9200/_cluster/settings -d '{
        "transient" : {
            "cluster.routing.allocation.exclude._ip" : "10.0.0.1"
        } }'</p>
  </blockquote>
  
  <p>It wasn't relocating any shards, so I ran the reroute command with the 'explain' option.  Can someone explain what the following text is saying ?</p>
  
  <pre><code>&gt;  "explanations" : [ {
  &gt;     "command" : "move",
  &gt;     "parameters" : {
  &gt;       "index" : "2015-09-20",
  &gt;       "shard" : 0,
  &gt;       "from_node" : "_dDn1SmqSquhMGgjti6vGg",
  &gt;       "to_node" : "OQBFMt17RaWboOzMnUy2jA"
  &gt;     },
  &gt;     "decisions" : [ {
  &gt;       "decider" : "same_shard",
  &gt;       "decision" : "YES",
  &gt;       "explanation" : "shard is not allocated to same node or host"
  &gt;     }, {
  &gt;       "decider" : "filter",
  &gt;       "decision" : "YES",
  &gt;       "explanation" : "node passes include/exclude/require filters"
  &gt;     }, {
  &gt;       "decider" : "replica_after_primary_active",
  &gt;       "decision" : "YES",
  &gt;       "explanation" : "shard is primary"
  &gt;     }, {
  &gt;       "decider" : "throttling",
  &gt;       "decision" : "YES",
  &gt;       "explanation" : "below shard recovery limit of [16]"
  &gt;     }, {
  &gt;       "decider" : "enable",
  &gt;       "decision" : "YES",
  &gt;       "explanation" : "allocation disabling is ignored"
  &gt;     }, {
  &gt;       "decider" : "disable",
  &gt;       "decision" : "YES",
  &gt;       "explanation" : "allocation disabling is ignored"
  &gt;     }, {
  &gt;       "decider" : "awareness",
  &gt;       "decision" : "NO",
  &gt;       "explanation" : "too many shards on nodes for attribute: [dc]"  }, {
  &gt;       "decider" : "shards_limit",
  &gt;       "decision" : "YES",
  &gt;       "explanation" : "total shard limit disabled: [-1] &lt;= 0"
  &gt;     }, {
  &gt;       "decider" : "node_version",
  &gt;       "decision" : "YES",
  &gt;       "explanation" : "target node version [1.4.5] is same or newer than source node version [1.4.5]"
  &gt;     }, {
  &gt;       "decider" : "disk_threshold",
  &gt;       "decision" : "YES",
  &gt;       "explanation" : "enough disk for shard on node, free: [1.4tb]"
  &gt;     }, {
  &gt;       "decider" : "snapshot_in_progress",
  &gt;       "decision" : "YES", "explanation" : "no snapshots are currently running"
  &gt;     
  </code></pre>