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The following page has been changed by SteveLoughran:
http://wiki.apache.org/hadoop/TroubleShooting

The comment on the change is:
creating a page

New page:
Some problems encountered in Hadoop and ways to go about solving them.

== NameNode startup fails ==

=== Exception when initializing the filesystem ==


{{{ERROR org.apache.hadoop.dfs.NameNode: java.io.EOFException
    at java.io.DataInputStream.readFully(DataInputStream.java:178)
    at org.apache.hadoop.io.UTF8.readFields(UTF8.java:106)
    at org.apache.hadoop.io.ArrayWritable.readFields(ArrayWritable.java:90)
    at org.apache.hadoop.dfs.FSEditLog.loadFSEdits(FSEditLog.java:433)
    at org.apache.hadoop.dfs.FSImage.loadFSEdits(FSImage.java:759)
    at org.apache.hadoop.dfs.FSImage.loadFSImage(FSImage.java:639)
    at org.apache.hadoop.dfs.FSImage.recoverTransitionRead(FSImage.java:222)
    at org.apache.hadoop.dfs.FSDirectory.loadFSImage(FSDirectory.java:79)
    at org.apache.hadoop.dfs.FSNamesystem.initialize(FSNamesystem.java:254)
    at org.apache.hadoop.dfs.FSNamesystem.<init>(FSNamesystem.java:235)
    at org.apache.hadoop.dfs.NameNode.initialize(NameNode.java:131)
    at org.apache.hadoop.dfs.NameNode.<init>(NameNode.java:176)
    at org.apache.hadoop.dfs.NameNode.<init>(NameNode.java:162)
    at org.apache.hadoop.dfs.NameNode.createNameNode(NameNode.java:846)
    at org.apache.hadoop.dfs.NameNode.main(NameNode.java:855)}}}

This is sometimes encountered if there is a corruption of the {{edits}} file 
in the transaction log. Try using a hex editor or equivalent to open
up 'edits' and get rid of the last record. In all cases, the last record
might not be complete so your NameNode is not starting. Once you update
your edits, start the NameNode and run {{{hadoop fsck /}}} to see if you
have any corrupt files and fix/get rid of them. 

Take a back up of {{{dfs.name.dir}}} before updating and playing around
with it.

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