我正在学习这个教程-http://www.ercoppa.org/linux-install-hadoop-220-on-ubuntu-linux-1304-single-node-cluster.htm
当我开始服务的时候。namenode没有启动。下面是我的namenode日志。我试着在google上搜索错误，但是找不到解决方法。我尝试删除目录中的namenode，甚至删除整个namenode数据目录并格式化namenode。但运气不好。我很感激你的帮助。

org.apache.hadoop.hdfs.server.common.Storage: Lock on /home/username/hadoop/data/namenode/in_use.lock acquired by nodename 25382@username-HP-ENVY-15-Notebook-PC  
org.mortbay.log: Stopped SelectChannelConnector@0.0.0.0:50070  
org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Stopping NameNode metrics system...  
org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system stopped.  
org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system stopped.  
org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system stopped.  
org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system stopped.  
java.io.IOException: NameNode is not formatted.
    at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:210)
    at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFSImage(FSNamesystem.java:787)
    at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFromDisk(FSNamesystem.java:568)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.loadNamesystem(NameNode.java:443)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:491)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:684)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:669)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1254)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1320)  
org.apache.hadoop.util.ExitUtil: Exiting with status 1  
INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG: