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From Xuan Dzung Doan <doanxuand...@yahoo.com>
Subject Inconsistency in namenode's and datanode's namespaceID
Date Wed, 02 Jul 2008 19:21:12 GMT
I was following the quickstart guide to run pseudo-distributed operations with Hadoop 0.16.4.
I got it to work successfully the first time. But I failed to repeat the steps (I tried to
re-do everything from re-formating the HDFS). Then by looking at the log files of the daemons,
I found out the datanode failed to start because its namespaceID didn't match with the namenode's.
I after that found that the namespaceID is stored in the text file VERSION under dfs/data/current
and dfs/name/current for the datanode and the namenode, respectively. The reformatting step
does change namespaceID of the namenode, but not for the datanode, and that's the cause for
the inconsistency. So after reformatting, if I manually update namespaceID for the datanode,
things will work totally fine again.

I guess there are probably others who had this same experience. Is it a bug in Hadoop 0.16.4?
If so, has it been taken care of in later versions?


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