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https://issues.apache.org/jira/browse/HDFS-16690?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mukund Thakur updated HDFS-16690:
---------------------------------
    Target Version/s: 3.3.9  (was: 3.4.0, 3.3.5)

> Automatically format new unformatted JournalNodes using JournalNodeSyncer 
> --------------------------------------------------------------------------
>
>                 Key: HDFS-16690
>                 URL: https://issues.apache.org/jira/browse/HDFS-16690
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: journal-node
>    Affects Versions: 3.4.0, 3.3.5
>         Environment: Demonstrated in a Kubernetes environment running Java 11.
>  # Start new cluster, but short 1 JN (minimum quorum, and the missing JN 
> won’t resolve). VERIFY:
>  - NN formats the 2 existing JN and stabilizes.  NOTE: Formatting using just 
> a quorum will be a separate submission
>  - Messages show sync between JN-0 and JN-1, and NN -> JN.
>  # Scale JN stateful set to add missing JN. VERIFY:
>  - New JN starts
>  - All other JN and all NN report IP address change (IP Address resolution).  
> NOTE: require HADOOP-18365 and HDFS-16688
>  - Messages show sync between all JN, and NN -> JN
>  - New JN is formatted at least once (possibly by multiple other JN)
>  - New JN storage directory is formatted only once
>  - New JN joins cluster (lastWriterEpoch is non-zero)
>            Reporter: Steve Vaughan
>            Assignee: Steve Vaughan
>            Priority: Major
>
> If an unformatted JournalNode is added to an existing JournalNode set, 
> instances of the JournalNodeSyncer are unable to sync to the new node.  When 
> a sync receives a JournalNotFormattedException, we can initiate a format 
> operation, and then retry the synchronization.
> Conceptually this means that the JournalNodes and their data can be managed 
> independently from the rest of the system, as the JournalNodes will 
> incorporate new JournalNode instances.  Once the new JournalNode is 
> formatted, it can participate in shared edits from the NameNodes. 
> I've been testing an update to the InterQJournalProtocol to add a format call 
> like that used by the NameNode.  Current tests include starting an HA cluster 
> from scratch, but with 2 JournalNode instances.  Once the cluster is up, I 
> can add the 3rd JournalNode (which is unformatted), and the other 2 
> JournalNodes will eventually attempt to sync which results in a formatting 
> and subsequent sync.



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