hadoop_异常_01_ Unable to determine address of the host-falling back to "localhost" address java.net.UnknownHostException: rayner

一、异常现象

安装好hadoop之后，执行格式化namenode命令时，抛出以下异常：

// :: WARN net.DNS: Unable to determine local hostname -falling back to "localhost"
java.net.UnknownHostException: rayner: rayner
        at java.net.InetAddress.getLocalHost(InetAddress.java:)
        at org.apache.hadoop.net.DNS.resolveLocalHostname(DNS.java:)
        at org.apache.hadoop.net.DNS.<clinit>(DNS.java:)
        at org.apache.hadoop.hdfs.server.namenode.NNStorage.newBlockPoolID(NNStorage.java:)
        at org.apache.hadoop.hdfs.server.namenode.NNStorage.newNamespaceInfo(NNStorage.java:)
        at org.apache.hadoop.hdfs.server.namenode.FSImage.format(FSImage.java:)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.format(NameNode.java:)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:)
Caused by: java.net.UnknownHostException: rayner
        at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method)
        at java.net.InetAddress$.lookupAllHostAddr(InetAddress.java:)
        at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:)
        at java.net.InetAddress.getLocalHost(InetAddress.java:)
        ...  more
// :: WARN net.DNS: Unable to determine address of the host-falling back to "localhost" address
java.net.UnknownHostException: rayner: rayner
        at java.net.InetAddress.getLocalHost(InetAddress.java:)
        at org.apache.hadoop.net.DNS.resolveLocalHostIPAddress(DNS.java:)
        at org.apache.hadoop.net.DNS.<clinit>(DNS.java:)
        at org.apache.hadoop.hdfs.server.namenode.NNStorage.newBlockPoolID(NNStorage.java:)
        at org.apache.hadoop.hdfs.server.namenode.NNStorage.newNamespaceInfo(NNStorage.java:)
        at org.apache.hadoop.hdfs.server.namenode.FSImage.format(FSImage.java:)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.format(NameNode.java:)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:)
Caused by: java.net.UnknownHostException: rayner
        at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method)
        at java.net.InetAddress$.lookupAllHostAddr(InetAddress.java:)
        at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:)
        at java.net.InetAddress.getLocalHost(InetAddress.java:)
        ...  more

二、异常原因

是因为更改了虚拟机的hostname

vim  /etc/sysconfig/network

而/etc/hosts  下的文件没有修改

三、异常解决

（1）编辑 /etc/hosts  文件

vim /etc/hosts 

（2）将 主机IP 和 对应的主机名称 进行映射

添加下图红框中内容

192.168.1.102  rayner

三、参考资料

1.Unable to determine local hostname -falling back to "localhost"