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From Markus Jelsma <markus.jel...@openindex.io>
Subject UnknownHostException namenode
Date Fri, 06 Jan 2012 14:22:54 GMT
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
	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(DistributedFileSystem.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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