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Hadoop:Name node and data node replacement

+3 votes
752 views

I am trying to understand,how to recover a Name node or Data node failure in case if those nodes are unable to come up due to unexpected issues.

Is there a way to replace Name node with new name node without loosing data.I mean new Name node should have all the data from original Name node. Similarly for Data node.

posted Dec 9, 2013 by Satish Mishra

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1 Answer

+2 votes

To recover a NN, you probably want to use the HA feature. If not, try writing your edits to a nfs volume in additional to the local fs.

There is no need to recover a DN. The NN compensates for a lost DN by using the other remaining replicas to create a new replica on another DN.

answer Dec 9, 2013 by Majula Joshi
Thanks for your response.
You mean NN will always try to maintain number of replicas as configured even if one DN goes down and unable to come up?
 
commented Dec 11, 2013 by anonymous
Yes you are right. It will periodically checks the under replicated blocks information and place those blocks on available data nodes if required.
commented Dec 11, 2013 by anonymous
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