Check the datanode logs, whether it is registered with namenode or not. At the same time you can check any problem occurred while initializing the datanode. If it registers successfully it shows that data node in the live nodes of the namenode UI.
Devaraj K ---------------------------------------------------------------------------- --------------------------------------------------------- This e-mail and its attachments contain confidential information from HUAWEI, which is intended only for the person or entity whose address is listed above. Any use of the information contained herein in any way (including, but not limited to, total or partial disclosure, reproduction, or dissemination) by persons other than the intended recipient(s) is prohibited. If you receive this e-mail in error, please notify the sender by phone or email immediately and delete it!ss _____ From: Sudharsan Sampath [mailto:sudha...@gmail.com] Sent: Tuesday, July 05, 2011 6:13 PM To: mapreduce-user@hadoop.apache.org Subject: MapReduce output could not be written Hi, In one of my jobs I am getting the following error. java.io.IOException: File X could only be replicated to 0 nodes, instead of 1 at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNam esystem.java:1282) at org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:469) at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl .java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:512) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:968) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:964) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:396) at org.apache.hadoop.ipc.Server$Handler.run(Server.java:962) and the job fails. I am running a single server that runs all the hadoop daemons. So only one datanode in my scenario. The datanode was up all the time. There is enough space on the disk. Even on debug level, I do not see any of the following logs Node X " is not chosen because the node is (being) decommissioned because the node does not have enough space because the node is too busy because the rack has too many chosen nodes Do anyone know of anyother scenario in which occur ? Thanks Sudharsan S