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From Markus Jelsma <markus.jel...@openindex.io>
Subject Re: UnknownHostException namenode
Date Sat, 07 Jan 2012 12:59:00 GMT

> Markus Jelsma wrote on 01/06/12 at 06:22:54 -0800:
> >Hi,
> >
> >We sometimes see tasks failing with the exception below. There are no
> >network issues and the domainname resolves normally. Also, all nodes have
> >a local DNS caching daemon running. Any idea why we see this error? It
> >usually happens when there is more than one job running on the cluster.
> >
> >We could, of course, add all nodes in /etc/hosts but i prefer not.
> >
> >java.net.UnknownHostException: unknown host: namenode
> 
> is 'namenode' here an fqdn? Both forward and reverse should resolve to
> the same name. If this is fine, then you may want to check your local
> caching resolver.

Yes, this is a a FQDN. We've checked pdnsd but nothing out of the ordinary so 
far. 

Will keep looking.
Thanks

> 
> >	at org.apache.hadoop.ipc.Client$Connection.<init>(Client.java:214)
> >	at org.apache.hadoop.ipc.Client.getConnection(Client.java:1192)
> >	at org.apache.hadoop.ipc.Client.call(Client.java:1046)
> >	at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:225)
> >	at $Proxy2.getProtocolVersion(Unknown Source)
> >	at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:396)
> >	at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:379)
> >	at org.apache.hadoop.hdfs.DFSClient.createRPCNamenode(DFSClient.java:118)
> >	at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:222)
> >	at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:187)
> >	at
> >
> >org.apache.hadoop.hdfs.DistributedFileSystem.initialize(DistributedFileSys
> >tem.java:89)
> >
> >	at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:1328)
> >	at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:65)
> >	at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1346)
> >	at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:244)
> >	at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:122)
> >	at org.apache.hadoop.mapred.Child$4.run(Child.java:254)
> >	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:1059)
> >
> >	at org.apache.hadoop.mapred.Child.main(Child.java:249)
> >
> >Thanks

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