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https://issues.apache.org/jira/browse/HDFS-13522?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16929700#comment-16929700
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Ayush Saxena commented on HDFS-13522:
-------------------------------------

Thanx [~crh] for the design. I started reading but got an initial doubt, 
regarding the need to split read and write routers. I think we can use only one 
kind of routers itself. The reason to split for observer read seems here too to 
differentiate call between active NN for write and Observer NN for read. 
Can this be not done in existing routers, we can check if the stateId is set, 
That means the client is using {{ObserverProxyProvider}} and we can direct the 
call to Observer NN and if not we can follow the normal flow as it is.
Let me know if I missed some fact here.

> Support observer node from Router-Based Federation
> --------------------------------------------------
>
>                 Key: HDFS-13522
>                 URL: https://issues.apache.org/jira/browse/HDFS-13522
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: federation, namenode
>            Reporter: Erik Krogen
>            Assignee: Chao Sun
>            Priority: Major
>         Attachments: HDFS-13522.001.patch, RBF_ Observer support.pdf, 
> Router+Observer RPC clogging.png, ShortTerm-Routers+Observer.png
>
>
> Changes will need to occur to the router to support the new observer node.
> One such change will be to make the router understand the observer state, 
> e.g. {{FederationNamenodeServiceState}}.



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