hadoop集群启动成功但live node为0

这两天用虚拟机搭建了hadoop集群环境，创建了三台虚拟机hadoop01，hadoop02，hadoop03，hadoop01代表Master，hadoop02以及hadoop03作为 Slave 节点。三台虚拟机都是centos7最小化安装。hadoop版本用的最新的版本2.7.2。
开始一切都很顺利，启动hadoop集群也成功启动，运行jps，三个节点对应的进程都成功启动，但是检查集群状态时发现live node 为0（如图）。

这个就让人很郁闷了，检查了下 Slave 节点日志，发现一些异常的地方：

2016-03-05 07:34:23,972 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Problem connecting to server: hadoop01/192.168.116.101:9000
2016-03-05 07:34:29,980 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: hadoop01/192.168.116.101:9000. Already tried 0 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS)
2016-03-05 07:34:30,985 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: hadoop01/192.168.116.101:9000. Already tried 1 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISEC