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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "CouldOnlyBeReplicatedTo" by SteveLoughran
Date Wed, 26 Oct 2011 11:35:46 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The "CouldOnlyBeReplicatedTo" page has been changed by SteveLoughran:
http://wiki.apache.org/hadoop/CouldOnlyBeReplicatedTo?action=diff&rev1=1&rev2=2

Comment:
note cause is also no disk capacity, with a different fix

  = Could Only Be Replicated To ... =
  
- A common message people see on startup is "could only be replicated to 0 nodes, instead
of 1".
+ A common message people see is "could only be replicated to 0 nodes, instead of ...".
  
  What does this mean? It means that the [[BlockReplication|Block Replication]] mechanism
of HDFS could not make any copies of a file it wanted to create. This can be caused by
   * No DataNode instances being up and running. Action: look at the servers, see if the processes
are running.
   * The DataNode instances cannot talk to the server, through networking or Hadoop configuration
problems. Action: look at the logs of one of the [[DataNode|DataNodes]].
   * Your DataNode instances have no hard disk space in their configured data directories.
Action: look at the dfs.data.dir list in the node configurations, verify that at least one
of the directories exists, and is writeable by the user running the Hadoop processes. Then
look at the logs.
+  * Your DataNode instances have run out of space. Look at the disk capacity via the Namenode
web pages. Delete old files. Compress under-used files. Buy more disks for existing servers
(if there is room), upgrade the existing servers to bigger drives, or add some more servers.

  
  This is not a problem in Hadoop, it is a problem in your cluster that you are going to have
to fix on your own. Sorry.
  

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