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https://issues.apache.org/jira/browse/YARN-1584?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13868231#comment-13868231
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Bikas Saha commented on YARN-1584:
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The duration of failover depends on how long ZK needs to figure out that the
leader is gone. Then notifying the new leader. Then new leader reading state.
Its not clear to me how any of these steps are faster with a admin failover
option.
Not quite. When the RM is asked to transition to active via the AdminService
(FORCE_USER) flag, then the AdminService can transition to standby and then
notify the elector to quitElection(). That API is present on the elector for
this specific purpose. The elector gives up participation in the leader
election process. This RM will remain in standby (because the elector is not
going to notify it anymore) until the admin ask it to
transitionToActive(FORCE_USER). Later, when the AdminService is asked to
transitionToActive() it can call the joinElection API on the elector to rejoin
the leader election and stay in the Standby state. The elector will join the
election and notify the RM to transitionToActive if it wins the election.
> Support explicit failover when automatic failover is enabled
> ------------------------------------------------------------
>
> Key: YARN-1584
> URL: https://issues.apache.org/jira/browse/YARN-1584
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: resourcemanager
> Affects Versions: 2.4.0
> Reporter: Karthik Kambatla
> Assignee: Karthik Kambatla
>
> YARN-1029 adds automatic failover support. However, users can't explicitly
> ask for a failover from one RM to the other without stopping the other RM.
> Stopping the RM until the other RM takes over and then restarting the first
> RM is more involving and exposes the RM-ensemble to SPOF for a longer
> duration.
> It would be nice to allow explicit failover through yarn rmadmin -failover
> command.
> PS: HDFS supports -failover option.
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