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https://issues.apache.org/jira/browse/HADOOP-10251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14581560#comment-14581560
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lvchuanwen commented on HADOOP-10251:
-------------------------------------
You can try the command hdfs haadmin -failover nn1 nn2 , and then see if the
active node nn1 is normal.
nn1 will always change state .active -> standby -> active -> standby .......
sorry for my poor english ,hope you can understand.thanks.
> Both NameNodes could be in STANDBY State if SNN network is unstable
> -------------------------------------------------------------------
>
> Key: HADOOP-10251
> URL: https://issues.apache.org/jira/browse/HADOOP-10251
> Project: Hadoop Common
> Issue Type: Bug
> Components: ha
> Affects Versions: 2.2.0
> Reporter: Vinayakumar B
> Assignee: Vinayakumar B
> Priority: Critical
> Fix For: 2.5.0
>
> Attachments: HADOOP-10251.patch, HADOOP-10251.patch,
> HADOOP-10251.patch, HADOOP-10251.patch, HADOOP-10251.patch
>
>
> Following corner scenario happened in one of our cluster.
> 1. NN1 was Active and NN2 was Standby
> 2. NN2 machine's network was slow
> 3. NN1 got shutdown.
> 4. NN2 ZKFC got the notification and trying to check for old active for
> fencing. (This took little more time, again due to slow network)
> 5. In between, NN1 got restarted by our automatic monitoring, and ZKFC made
> it Active.
> 6. Now NN2 ZKFC got Old Active as NN1 and it did graceful fencing of NN1 to
> STANBY.
> 7. Before writing ActiveBreadCrumb to ZK, NN2 ZKFC got session timeout and
> got shutdown before making NN2 Active.
> *Now cluster having both NameNodes as STANDBY.*
> NN1 ZKFC still thinks that its nameNode is in Active state.
> NN2 ZKFC waiting for election.
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