我是hadoop新手，我尝试在我的虚拟机中安装hadoop3.0，在我配置hadoop之后，然后尝试：

hdfs namenode ‐format

并得到输出：

2017-12-26 00:20:56,255 INFO namenode.NameNode: STARTUP_MSG: 
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG:   host = localhost/127.0.0.1
STARTUP_MSG:   args = [‐format]
STARTUP_MSG:   version = 3.0.0
STARTUP_MSG:   classpath = /opt/hadoop-3.0.0/etc/hadoop:/opt/hadoop-3.0.0/share/hadoop/common/lib/xz-1.0.jar:/opt/hadoop-3.0.0/share/hadoop/common/lib/kerby-util-1.0.1.jar:   .............   hadoop-yarn-applications-unmanaged-am-launcher-3.0.0.jar:/opt/hadoop-3.0.0/share/hadoop/yarn/hadoop-yarn-registry-3.0.0.jar
STARTUP_MSG:   build = https://git-wip-us.apache.org/repos/asf/hadoop.git -r c25427ceca461ee979d30edd7a4b0f50718e6533; compiled by 'andrew' on 2017-12-08T19:16Z
STARTUP_MSG:   java = 1.8.0_151

************************************************************/

2017-12-26 00:20:56,265 INFO namenode.NameNode: registered UNIX signal handlers for [TERM, HUP, INT]
2017-12-26 00:20:56,269 INFO namenode.NameNode: createNameNode [‐format]
Usage: hdfs namenode [-backup] | 
        [-checkpoint] | 
        [-format [-clusterid cid ] [-force] [-nonInteractive] ] | 
        [-upgrade [-clusterid cid] [-renameReserved<k-v pairs>] ] | 
        [-upgradeOnly [-clusterid cid] [-renameReserved<k-v pairs>] ] | 
        [-rollback] | 
        [-rollingUpgrade <rollback|started> ] | 
        [-importCheckpoint] | 
        [-initializeSharedEdits] | 
        [-bootstrapStandby [-force] [-nonInteractive] [-skipSharedEditsCheck] ] | 
        [-recover [ -force] ] | 
        [-metadataVersion ]

2017-12-26 00:20:56,365 INFO namenode.NameNode: SHUTDOWN_MSG: 
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at localhost/127.0.0.1

************************************************************/

我将hdfs-site.xml配置如下：

<configuration>

  <property>
    <name>dfs.replication</name>
    <value>1</value>
  </property>

  <property>
    <name>dfs.namenode.name.dir</name>
    <value>/home/dan/hadoop_data/namenode</value>
  </property>
  <property>
    <name>dfs.datanode.data.dir</name>
    <value>/home/dan/hadoop_data/datanode</value>
  </property>

</configuration>

当我启动namenode服务时，它会失败并记录tell:2017-12-26 00:03:41331 info org.apache.hadoop.util.exitutil:正在退出，状态为1:java.io.ioexception:namenode未格式化。2017-12-26 00:03:41337 info org.apache.hadoop.hdfs.server.namenode.namenode:关机\u消息：
有人能告诉我怎么解决这个问题吗？
提前谢谢！