Hadoop启动错误：50010端口被占用

今天启动hadoop的时候遇到两个错误：

1. ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: java.io.IOException: Incompatible namespaceIDs in ...

　　namenode namespaceID = 1691922584; datanode namespaceID = 614022826

数据格式不匹配，需要进行 hadoop namenode -format

2. 2011-05-1 14:30:41,855 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: java.net.BindException: Problem binding to /0.0.0.0:50010 : Address already in useat org.apache.hadoop.ipc.Server.bind(Server.java:190)at 　　org.apache.hadoop.hdfs.server.datanode.DataNode.startDataNode(DataNode.java:309)at 　　org.apache.hadoop.hdfs.server.datanode.DataNode.(DataNode.java:216)

　　50010端口被占用，在hdfs-site.xml中改成其他端口号

dfs.datanode.address

0.0.0.0:50010

The address where the datanode server will listen to.

If the port is 0 then the server will start on a free port.

　　类似的，还有50030端口被占用的情况：

　　2011-05-1 14:30:43,931 INFO org.apache.hadoop.http.HttpServer: Port returned by webServer.getConnectors()[0].getLocalPort() before open() is -1. Opening the listener on 50030

　　2011-05-1 14:30:43,933 FATAL org.apache.hadoop.mapred.JobTracker: java.net.BindException: Address already in use

　　　　at sun.nio.ch.Net.bind(NativeMethod)

　　　　at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:119)

　　在mapred-default.xml中修改下端口号：

mapred.job.tracker.http.address

0.0.0.0:50030

The job tracker http server address and port

the server will listen on.If the port is 0 then the server

will start on a free port.