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Posted to common-commits@hadoop.apache.org by Apache Wiki <wi...@apache.org> on 2011/06/16 19:56:01 UTC

[Hadoop Wiki] Trivial Update of "FAQ" by QwertyManiac

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The "FAQ" page has been changed by QwertyManiac:
http://wiki.apache.org/hadoop/FAQ?action=diff&rev1=104&rev2=105

   1. Restart the HDFS
  
  == What does "file could only be replicated to 0 nodes, instead of 1" mean? ==
- The NameNode does not have any available !DataNodes.  This can be caused by a wide variety of reasons.  Check the DataNode logs, the NameNode logs, network connectivity, ...
+ The NameNode does not have any available !DataNodes.  This can be caused by a wide variety of reasons.  Check the DataNode logs, the NameNode logs, network connectivity, ... Please see the page: CouldOnlyBeReplicatedTo
  
  == If the NameNode loses its only copy of the fsimage file, can the file system be recovered from the DataNodes? ==
  No.  This is why it is very important to configure [[http://hadoop.apache.org/hdfs/docs/current/hdfs-default.html#dfs.namenode.name.dir|dfs.namenode.name.dir]] to write to two filesystems on different physical hosts, use the SecondaryNameNode, etc.