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https://issues.apache.org/jira/browse/HDFS-1623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13039019#comment-13039019
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Sanjay Radia commented on HDFS-1623:
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> How does NN fail-over impact federation? Eg does viewfs have any special
> requirements as a client?
In case of federation, each NN needs its own warm or hot failover. Cannot do
N+k failover because of the large memory requirements for a NN unless one wants
to limit it to cold failover.
Viewfs is separate layer and not required for federation; one could choose to
use symbolic links or one could choose to not provide a global namespace. But
if one were to use viewfs, I am not aware of any *additional* failover issues.
Viewfs has bindings like: /user ->hdfs://nnOfUser/
The failover issues are the same as if hdfs://nnofUser was your default file
system.
> High Availability Framework for HDFS NN
> ---------------------------------------
>
> Key: HDFS-1623
> URL: https://issues.apache.org/jira/browse/HDFS-1623
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Sanjay Radia
> Assignee: Sanjay Radia
> Attachments: HDFS-High-Availability.pdf, NameNode HA_v2.pdf, Namenode
> HA Framework.pdf
>
>
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