问题

1. 使用logstash 同步mysql 到 es后，发现 同步新建的index 状态为yellow

2. 查询分片状态，发现所有副本分区都是UNASSIGNED状态
   curl -XGET http://localhost:9200/_cat/shards | grep UNASSIGNED

or 使用elastic-head 查看集群状态可以看到

3. 查看日志：
   [2017-10-28 12:21:06,828][INFO ][cluster.routing.allocation.decider] [node-1] low disk watermark [85%] exceeded on [Uoy7PyXERAGZXOTjNEDGwg][node-1][/Users/baidu/IdeaProjects/git/elasticsearch2-node1/data/my-application/nodes/0] free: 12.4gb[11.1%], replicas will not be assigned to this node

4. 从日志可以看出是磁盘空间不够导致的, 调整磁盘最低限制解决
   curl -XPUT localhost:9200/_cluster/settings -d '
   {
   "transient" : {
   "cluster.routing.allocation.disk.threshold_enabled" : true
   }
   }'

curl -XPUT localhost:9200/_cluster/settings -d '
{
"transient" : {
"cluster.routing.allocation.disk.watermark.low" : 0.95
}
}'