Hadoop启动HDFS时DataNode未启动

在用$HADOOP_HOME/sbin/start-dfs.sh启动HDFS时发现只有NameNode和SecondaryNameNode启动,没有DataNode。

查看logs下的DataNode日志中显示如下错误：

WARN org.apache.hadoop.hdfs.server.datanode.DataNode: IOException in offerService
java.io.EOFException: End of File Exception between local host is: "hadoop/127.0.0.1"; destination host is: "hadoop":8020; : java.io.EOFException; For more details see:  http://wiki.apache.org/hadoop/EOFException
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
        at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:791)
        at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:764)
        at org.apache.hadoop.ipc.Client.call(Client.java:1508)
        at org.apache.hadoop.ipc.Client.call(Client.java:1441)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:230)
        at com.sun.proxy.$Proxy16.sendHeartbeat(Unknown Source)
        at org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB.sendHeartbeat(DatanodeProtocolClientSideTranslatorPB.java:154)
        at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.sendHeartBeat(BPServiceActor.java:406)

查资料得知如下解决办法：

修改/etc/hosts中的内容，注意要删除掉多余项，并注释掉127.0.0.1 localhost回环地址，这里我已经把127.0.0.1注释了，应该是多余项没有删掉引起的。

此外若/etc/hostname中的名称不一致也要修改并重启。

参考资料：https://blog.csdn.net/qqq824908000/article/details/70789303