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From "Vinay (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-10251) Both NameNodes could be in STANDBY State if SNN network is unstable
Date Tue, 04 Feb 2014 17:18:09 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-10251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13890860#comment-13890860

Vinay commented on HADOOP-10251:

Hi, Can someone please review the patch.. 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: Vinay
>            Assignee: Vinay
>            Priority: Critical
>         Attachments: 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 NN2 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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