[hadoop@hadoop_master sbin]$ ./start-dfs.sh
Incorrect configuration: namenode address dfs.namenode.servicerpc-address or dfs.namenode.rpc-address is not configured.
Starting namenodes on []
而且每台機器都啟動了namenode，datanode，但是都沒有啟動成功。。。
jps看不到任何東西。啟動失敗
實在是莫名其妙，配置檢查了一遍又一遍，沒發現任何問題。。
后來考慮了下是不是機器名得問題，就將hadoop_master 修改成 hadoopmaster，所有得機器名都去掉了下划線，結果（真是奇葩得問題）。。
[hadoop@hadoopmaster sbin]$ ./start-dfs.sh
Starting namenodes on [hadoopmaster]
hadoopmaster: starting namenode, logging to /app/hadoop/hadoop-2.2.0/logs/hadoop-hadoop-namenode-hadoopmaster.out
hadoopslave2: starting datanode, logging to /app/hadoop/hadoop-2.2.0/logs/hadoop-hadoop-datanode-hadoopslave2.out
hadoopslave1: starting datanode, logging to /app/hadoop/hadoop-2.2.0/logs/hadoop-hadoop-datanode-hadoopslave1.out
hadoopmaster: starting datanode, logging to /app/hadoop/hadoop-2.2.0/logs/hadoop-hadoop-datanode-hadoopmaster.out
hadooporacle: starting datanode, logging to /app/hadoop/hadoop-2.2.0/logs/hadoop-hadoop-datanode-hadooporacle.out
Starting secondary namenodes [hadoopmaster]
hadoopmaster: starting secondarynamenode, logging to /app/hadoop/hadoop-2.2.0/logs/hadoop-hadoop-secondarynamenode-hadoopmaster.out