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https://issues.apache.org/jira/browse/HDFS-4173?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13501346#comment-13501346
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Todd Lipcon commented on HDFS-4173:
-----------------------------------
Hey Colin. I'm not sure this is the right place for this new code -- the
{{initJournals}} function gets called even when the journals are being
initialized for _read_ -- so this would cause the NN to initialize the shared
edits dir on standby startup, wouldn't it? ie if we configure for HA and don't
run the explicit -initializeSharedEdits, I don't think it's appropriate to
auto-format, since it could end up with a race where both nodes try to format
and end up formatting each other's dirs. Am I missing something?
At the least we should probably add a comment in
{{FSImage.recoverTransitionRead}} which points out that non-file storage
directories will get formatted when the edit log is initialized.
> If the NameNode has already been formatted, but a QuroumJournal has not,
> auto-format it on startup
> --------------------------------------------------------------------------------------------------
>
> Key: HDFS-4173
> URL: https://issues.apache.org/jira/browse/HDFS-4173
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: journal-node, name-node
> Affects Versions: 2.0.3-alpha
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Priority: Minor
> Attachments: HDFS-4173.001.patch
>
>
> If we have multiple edit log directories, and some of them are formatted, but
> others are not, we format the unformatted ones. However, when we implemented
> QuorumJournalManager, we did not extend this behavior to it. It makes sense
> to do this.
> One use case is if you want to add a QuorumJournalManager URI
> ({{journal://}}) to an existing {{NameNode}}, without reformatting
> everything. There is currently no easy way to do this, since {{namenode
> \-format}} will nuke everything, and there's no other way to format the
> {{JournalNodes}}.
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