Distcp will run as mapreduce job. Here tasktrackers required the hostname mappings to contact to other nodes. Please configure the mapping correctly in both the machines and try. egards, Uma
----- Original Message ----- From: trang van anh <anh...@vtc.vn> Date: Wednesday, October 5, 2011 1:41 pm Subject: Re: Error using hadoop distcp To: common-user@hadoop.apache.org > which host run the task that throws the exception ? ensure that > each > data node know another data nodes in hadoop cluster-> add "ub16" > entry > in /etc/hosts on where the task running. > On 10/5/2011 12:15 PM, praveenesh kumar wrote: > > I am trying to use distcp to copy a file from one HDFS to another. > > > > But while copying I am getting the following exception : > > > > hadoop distcp hdfs://ub13:54310/user/hadoop/weblog > > hdfs://ub16:54310/user/hadoop/weblog > > > > 11/10/05 10:41:01 INFO mapred.JobClient: Task Id : > > attempt_201110031447_0005_m_000007_0, Status : FAILED > > java.net.UnknownHostException: unknown host: ub16 > > at > org.apache.hadoop.ipc.Client$Connection.<init>(Client.java:195)> > at org.apache.hadoop.ipc.Client.getConnection(Client.java:850) > > at org.apache.hadoop.ipc.Client.call(Client.java:720) > > at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:220) > > at $Proxy1.getProtocolVersion(Unknown Source) > > at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:359) > > at > > > org.apache.hadoop.hdfs.DFSClient.createRPCNamenode(DFSClient.java:113)> > at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:215) > > at > org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:177)> > at > > > org.apache.hadoop.hdfs.DistributedFileSystem.initialize(DistributedFileSystem.java:82)> > at > > > org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:1378)> > at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:66) > > at > org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1390)> > at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:196) > > at org.apache.hadoop.fs.Path.getFileSystem(Path.java:175) > > at > > > org.apache.hadoop.mapred.FileOutputCommitter.setupJob(FileOutputCommitter.java:48)> > at > > > org.apache.hadoop.mapred.OutputCommitter.setupJob(OutputCommitter.java:124)> > at org.apache.hadoop.mapred.Task.runJobSetupTask(Task.java:835) > > at org.apache.hadoop.mapred.MapTask.run(MapTask.java:296) > > at org.apache.hadoop.mapred.Child.main(Child.java:170) > > > > Its saying its not finding ub16. But the entry is there in > /etc/hosts files. > > I am able to ssh both the machines. Do I need password less ssh > between> these two NNs ? > > What can be the issue ? Any thing I am missing before using > distcp ? > > > > Thanks, > > Praveenesh > > > >
