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https://issues.apache.org/jira/browse/HDFS-14067?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16685901#comment-16685901
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Erik Krogen commented on HDFS-14067:
------------------------------------
{quote}
In our case, I do see some potential inconsistency. Currently the
ZKFailoverController only tracks active and standby state. And, if we manually
transition a standby to observer, ZK will still keep the old state and even
make the observer eligible for election, which is incorrect. This somewhat
overlaps with HDFS-13182.
{quote}
Great, thanks for the explanation [~csun]! That sounds like exactly the type of
concern I had but didn't know enough about ZKFailoverController to know exactly
where the issue might be.
I don't think we have an easy way to solve this until HDFS-13182 is completed.
Personally, I feel it makes more sense for administrators to transition in/out
of observer using {{--forcemanual}} for now to force them to consider the
potential effects of this inconsistency.
> Allow manual failover between standby and observer
> --------------------------------------------------
>
> Key: HDFS-14067
> URL: https://issues.apache.org/jira/browse/HDFS-14067
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Chao Sun
> Assignee: Chao Sun
> Priority: Major
> Attachments: HDFS-14067-HDFS-12943.000.patch
>
>
> Currently if automatic failover is enabled in a HA environment, transition
> from standby to observer would be blocked:
> {code}
> [hdfs@*** hadoop-3.3.0-SNAPSHOT]$ bin/hdfs haadmin -transitionToObserver ha2
> Automatic failover is enabled for NameNode at ****
> 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.
> {code}
> We should allow manual transition between standby and observer in this case.
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