hadoop-common-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
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.).
>
>   


Mime
View raw message