2013-08-20 10:36:17,728 INFO org.apache.hadoop.http.HttpServer: listener.getLocalPort() returned 50070 webServer.getConnectors()[0].getLocalPort() returned 50070
2013-08-20 10:36:17,728 INFO org.apache.hadoop.http.HttpServer: Jetty bound to port 50070
2013-08-20 10:36:17,728 INFO org.mortbay.log: jetty-6.1.26
2013-08-20 10:36:18,118 INFO org.mortbay.log: Started SelectChannelConnector@0.0.0.0:50070
2013-08-20 10:36:18,119 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: Web-server up at: 0.0.0.0:50070
2013-08-20 10:36:18,119 INFO org.apache.hadoop.ipc.Server: IPC Server Responder: starting
2013-08-20 10:36:18,120 INFO org.apache.hadoop.ipc.Server: IPC Server listener on 49000: starting
2013-08-20 10:36:18,121 INFO org.apache.hadoop.ipc.Server: IPC Server handler 0 on 49000: starting
2013-08-20 10:36:18,121 INFO org.apache.hadoop.ipc.Server: IPC Server handler 1 on 49000: starting
2013-08-20 10:36:18,121 INFO org.apache.hadoop.ipc.Server: IPC Server handler 2 on 49000: starting
2013-08-20 10:36:18,122 INFO org.apache.hadoop.ipc.Server: IPC Server handler 3 on 49000: starting
2013-08-20 10:36:18,122 INFO org.apache.hadoop.ipc.Server: IPC Server handler 4 on 49000: starting
2013-08-20 10:36:18,122 INFO org.apache.hadoop.ipc.Server: IPC Server handler 5 on 49000: starting
2013-08-20 10:36:18,122 INFO org.apache.hadoop.ipc.Server: IPC Server handler 6 on 49000: starting
2013-08-20 10:36:18,123 INFO org.apache.hadoop.ipc.Server: IPC Server handler 7 on 49000: starting
2013-08-20 10:36:18,123 INFO org.apache.hadoop.ipc.Server: IPC Server handler 8 on 49000: starting
2013-08-20 10:36:18,128 INFO org.apache.hadoop.ipc.Server: IPC Server handler 9 on 49000: starting
2013-08-20 10:36:22,717 ERROR org.apache.hadoop.security.UserGroupInformation: PriviledgedActionException as:hadoop cause:java.io.IOException: File /usr/hadoop_dir/tmp/mapred/system/jobtracker.info could only be replicated to 0 nodes, instead of 1
2013-08-20 10:36:22,718 INFO org.apache.hadoop.ipc.Server: IPC Server handler 4 on 49000, call addBlock(/usr/hadoop_dir/tmp/mapred/system/jobtracker.info, DFSClient_NONMAPREDUCE_1570390041_1, null) from 192.168.2.99:56700: error: java.io.IOException: File /usr/hadoop_dir/tmp/mapred/system/jobtracker.info could only be replicated to 0 nodes, instead of 1
java.io.IOException: File /usr/hadoop_dir/tmp/mapred/system/jobtracker.info could only be replicated to 0 nodes, instead of 1
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:1920)
at org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:783)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:587)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1432)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1428)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1190)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1426)
解决方案：
1、将masters与slaves中的主机配置为IP地址。
2、网上也有说防火墙没有关，也请检查一下。
3、重新格式化namenode hadoop namenode -format，并检查version文件中的ID
4、检查core-stite.xml mapred-site.xml 文件地址换成IP
5、检查相关日志，查看错误信息
6、注意datanode目录权限一定是 755
7、也有可能是java的bug引起的