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From Adarsh Sharma <adarsh.sha...@orkash.com>
Subject Re: Reason of Formatting Namenode
Date Thu, 10 Mar 2011 05:48:58 GMT
Thanks Harsh, i.e why if we again format namenode after loading some 
data INCOMATIBLE NAMESPACE ID's error occurs.

Best Regards,

Adarsh Sharma

Harsh J wrote:
> Formatting the NameNode initializes the FSNameSystem in the
> dfs.name.dir directories, to prepare for use.
> The format command typically writes a VERSION file that specifies what
> the NamespaceID for this FS instance is, what was its ctime, and what
> is the version (of the file's layout) in use.
> This is helpful in making every NameNode instance unique, among other
> things. DataNode blocks carry the namespace-id information that lets
> them relate blocks to a NameNode (and thereby validate, etc.).

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