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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "CouldOnlyBeReplicatedTo" by SteveLoughran
Date Thu, 16 Jun 2011 15:52:02 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:

explain the could only be replicated message

New page:
= Could Only Be Replicated To ... =

A common message people see on startup 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.

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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