hadoop重启虚机后hdfs中数据丢失，需要重新格式化问题

1，虚机每次重启后，如果不格式化namenode，就错误，日志如下：

INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Registered FSNamesystemStateMBean and NameNodeMXBean  
INFO org.apache.hadoop.hdfs.server.namenode.NameNode: Caching file names occuring more than 10 times  INFO org.apache.hadoop.hdfs.server.common.Storage: Storage directory /tmp/hadoop-sylar/dfs/name does not exist. ERROR org.apache.hadoop.hdfs.server.namenode.FSNamesystem: FSNamesystem initialization failed. org.apache.hadoop.hdfs.server.common.InconsistentFSStateException: Directory /tmp/hadoop-sylar/dfs/name is in an inconsistent state: storage directory does not exist or is not accessible. 

2，解决方法，重新格式化：

~]$bin/hadoop namenode -format

3, 如果想彻底消除错误，并且每次重启机器不格式化，需要修改core-site.xml 和 hdfs-site.xml， 如下：

vm1:~/hadoop/conf$ cat core-site.xml

<?xml version="1.0"?>

<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Put site-specific property overrides in this file. -->

<configuration>

<property>

<name>fs.default.name</name>

<value>hdfs://192.168.1.105:9000</value>

</property>

<property>  

    <name>hadoop.tmp.dir</name>  

    <value>/home/hadoop/filesystem/tmp</value>  

    <description> temporary directories.</description>  

</property>  

<property>  

    <name>dfs.name.dir</name>  

    <value>/home/hadoop/filesystem/name</value>  

    <description>where on the local filesystem the DFS name node should store the name table</description>  

</property>  

<property>  

    <name>dfs.data.dir</name>  

    <value>/home/hadoop/filesystem/data</value>  

    <description>where on the local filesystem an DFS data node should store its blocks.</description>  

</property>  

   

</configuration>

vm1:~/hadoop/conf$

~/hadoop/conf$ cat hdfs-site.xml

<?xml version="1.0"?>

<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Put site-specific property overrides in this file. -->

<configuration>

<property>

<name>dfs.replication</name>

<value>1</value>

<name>dfs.permissions</name>

<value>false</value>

</property>

</configuration>