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https://issues.apache.org/jira/browse/HDFS-6452?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14010631#comment-14010631
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Gera Shegalov commented on HDFS-6452:
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Hi Aaron, the net improvement should be in the overhead smoothness over time.
E.g., we will smooth the storm of {{StandbyException: Operation category READ
is not supported in state standby}}
[~jingzhao], this is targeted for deployments with automatic failover where the
emphasis is on not trying to watch what NN is active all the time.
> ConfiguredFailoverProxyProvider should randomize currentProxyIndex on
> initialization
> ------------------------------------------------------------------------------------
>
> Key: HDFS-6452
> URL: https://issues.apache.org/jira/browse/HDFS-6452
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: ha, hdfs-client
> Affects Versions: 2.4.0
> Reporter: Gera Shegalov
> Assignee: Gera Shegalov
>
> We observe that the clients iterate proxies in the fixed order. Depending on
> the order of namenodes in dfs.ha.namenodes.<nameservice> (e.g. 'nn1,nn2') and
> the current standby (nn1), all the clients will hit nn1 first, and then
> failover to nn2. Chatting with [~lohit] we think we can simply select the
> initial value of {{currentProxyIndex}} randomly, and keep the logic of
> {{performFailover}} of iterating from left-to-right. This should halve the
> unnecessary load on standby NN.
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