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https://issues.apache.org/jira/browse/HDFS-2223?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13082771#comment-13082771
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Todd Lipcon commented on HDFS-2223:
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bq. Should FSImage.namesystem be removed?
Yes - it is removed in this patch. I wasn't able to easily remove it from
BackupImage at this point, without changing a bunch of the BN around. So, I
left it in the subclass only.
bq. Why not container for FSDirectory, FSImage, FSEditlog, as they are very
closely related to namespace.
bq. Should NNStorage belong to NameNode?
I think FSEditLog still belongs below FSImage, as it's part of the "image on
disk" in a sense, and their lifecycle is tightly related.
Moving NNStorage up into NameNode does make a certain amount of sense to me,
but I didn't want to bite off too much in one patch.
Do you think the changes in the attached patch are good, even if they're not a
complete cleanup of everything? If so, let's commit this and then do some more
work in another JIRA, just so each small improvement is easy to review?
> Untangle depencencies between NN components
> -------------------------------------------
>
> Key: HDFS-2223
> URL: https://issues.apache.org/jira/browse/HDFS-2223
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: name-node
> Affects Versions: 0.23.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Attachments: hdfs-2223-1.txt, hdfs-2223-2.txt, hdfs-2223-3.txt,
> hdfs-2223-4.txt
>
>
> Working in the NN a lot for HA (HDFS-1623) I've come across a number of
> situations where the tangled dependencies between NN components has been
> problematic for adding new features and for testability. It would be good to
> untangle some of these and clarify what the distinction is between the
> different components: NameNode, FSNamesystem, FSDirectory, FSImage,
> NNStorage, and FSEditLog
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