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Hadoop, mail # user - Namenode corruption: need help quickly please


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Re: Namenode corruption: need help quickly please
Allen Wittenauer 2010-10-26, 03:04

On Oct 25, 2010, at 5:30 PM, phil young wrote:
> We and others have seen the following error. Apparently it occurs when
> there's some change resulting in a difference in the "build" versions. This
> is not DFS corruption but may apper to be so because the master and task
> tracker processes start fine, but the
> DataNodes<https://twiki.tripadvisor.com/bin/edit/Development/DataNodes?topicparent=Development.HadoopTroubleshooting;nowysiwyg=0>report
> the following error:

It actually *can* lead to a "sort of" DFS corruption if the NN and DN versions are too far apart and a block conversion was required.  i.e., 0.21 vs 0.20 .  In that scenario, you can only roll forward, not back.  If you really wanted the older version, then you are a bit SOL, as there is no roll back without a snapshot being taken beforehand.