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https://issues.apache.org/jira/browse/HDFS-8277?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14586585#comment-14586585
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Arpit Agarwal commented on HDFS-8277:
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bq. NN stays in safemode until one more manual request is made to come out, or
it gets restarted. So there is no need of edit logging for this. Right?
Hi [~vinayrpet] unfortunately this is is a broken especially with HA. If the
command succeeds on just one NN the state is unpredictable. E.g. if SBN is
temporarily unavailable and then the primary NN crashes then we will no longer
be in safe-mode after failover.
bq. But this going to break the compatibility, by breaking the behaviour of
keeping the NN in safemode even after restart.
Agreed that it will be incompatible. However the halfway fix to issue the
command to just the active is worse. Perhaps we don't change anything for now.
> Safemode enter fails when Standby NameNode is down
> --------------------------------------------------
>
> Key: HDFS-8277
> URL: https://issues.apache.org/jira/browse/HDFS-8277
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: ha, HDFS, namenode
> Affects Versions: 2.6.0
> Environment: HDP 2.2.0
> Reporter: Hari Sekhon
> Assignee: surendra singh lilhore
> Priority: Minor
> Attachments: HDFS-8277-safemode-edits.patch, HDFS-8277.patch,
> HDFS-8277_1.patch, HDFS-8277_2.patch, HDFS-8277_3.patch, HDFS-8277_4.patch
>
>
> HDFS fails to enter safemode when the Standby NameNode is down (eg. due to
> AMBARI-10536).
> {code}hdfs dfsadmin -safemode enter
> safemode: Call From nn2/x.x.x.x to nn1:8020 failed on connection exception:
> java.net.ConnectException: Connection refused; For more details see:
> http://wiki.apache.org/hadoop/ConnectionRefused{code}
> This appears to be a bug in that it's not trying both NameNodes like the
> standard hdfs client code does, and is instead stopping after getting a
> connection refused from nn1 which is down. I verified normal hadoop fs writes
> and reads via cli did work at this time, using nn2. I happened to run this
> command as the hdfs user on nn2 which was the surviving Active NameNode.
> After I re-bootstrapped the Standby NN to fix it the command worked as
> expected again.
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