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Hadoop, mail # user - Error using hadoop distcp


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Re: Error using hadoop distcp
bejoy.hadoop@... 2011-10-05, 08:25
Hi praveenesh
             Can you try repeating the distcp using IP instead of host name. From the error looks like an RPC exception not able to identify the host, so I believe it can't be due to not setting a password less ssh. Just try it out.
Regards
Bejoy K S

-----Original Message-----
From: trang van anh <[EMAIL PROTECTED]>
Date: Wed, 05 Oct 2011 14:06:11
To: <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
Subject: Re: Error using hadoop distcp

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
>