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https://issues.apache.org/jira/browse/HDFS-12943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16687651#comment-16687651
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xiangheng commented on HDFS-12943:
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Thanks [~csun],I have tried this way but failed
* one workaround is to not launch ZK failover controller on the host where the
observer is at. Let me know if this works for you.
i have three namenode (nn1,nn2,nn3),if i launch ZK failover controller between
nn1 and nn2,and transform the state of nn3 from standby to observer,it will be
failed.
{{Refusing to manually manage HA state, since it may cause}}
{{a split-brain scenario or other incorrect state.}}
{{If you are very sure you know what you are doing, please}}
{{specify the --forcemanual flag.}}
{{[~journal]# hdfs haadmin -transitionToObserver --forcemanual nn3}}
{{transitionToObserver: incorrect arguments}}
i will focus on HDFS-14067, HDFS-13182 and HDFS-14059,thanks for your
suggestions.
> Consistent Reads from Standby Node
> ----------------------------------
>
> Key: HDFS-12943
> URL: https://issues.apache.org/jira/browse/HDFS-12943
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: hdfs
> Reporter: Konstantin Shvachko
> Priority: Major
> Attachments: ConsistentReadsFromStandbyNode.pdf,
> ConsistentReadsFromStandbyNode.pdf,
> TestPlan-ConsistentReadsFromStandbyNode.pdf
>
>
> StandbyNode in HDFS is a replica of the active NameNode. The states of the
> NameNodes are coordinated via the journal. It is natural to consider
> StandbyNode as a read-only replica. As with any replicated distributed system
> the problem of stale reads should be resolved. Our main goal is to provide
> reads from standby in a consistent way in order to enable a wide range of
> existing applications running on top of HDFS.
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