Ive been trying to understand federation in hadoop for a while now. My question is lets say I have two NameNodes NN1 and NN2, NN1 is managing the finance namespace NN2 is managing the IT namespace. If NN1 goes down will I still have access to the finance namespace which NN1 maintained earlier. If yes how??
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No , We can't access finance namespace. If a NameNode or namespace is deleted, the corresponding block pool which is residing on the DataNodes will also be deleted.
For more information refer this
https://hortonworks.com/blog/an-introduction-to-hdfs-federation/
https://hadoop.apache.org/docs/r2.7.2/hadoop-project-dist/hadoop-hdfs/Federation.html
Ramprakash
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If NN1 goes down will I still have access to the finance namespace which NN1 maintained earlier. If yes how??
If you configure only Active Namenode without Standby Namenode, you can't access finance Namespace once Active Namenode goes down.
If you configure Standby Namenode, then Standby Namenode will become active Namenode and you can access finance Namespace.
Refer to below posts for more details:
Ravindra babu
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