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https://issues.apache.org/jira/browse/HDFS-3092?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13252895#comment-13252895
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Bikas Saha commented on HDFS-3092:
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Todd, I was going to post this same comment on HDFS-3077 because I did not see
2 phase commits mentioned there either even though the initial comments
mentioned implementing ZAB. The doc did mention standby node tailing as a
requirement but it wasn't clear how this is being achieved in the absence of a
coordinated distributed commit.
bq. That's my plan in HDFS-3077, and in fact that's the current behavior of the
SBN, even when operating on NFS.
Hari updated me offline that standby NN currently tails only the finalized
edits. So this works fine. By 'my plan' are you referring to an API on the
journal node to read latest edits that replaces the current standby NN tailing
code?
> Enable journal protocol based editlog streaming for standby namenode
> --------------------------------------------------------------------
>
> Key: HDFS-3092
> URL: https://issues.apache.org/jira/browse/HDFS-3092
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: ha, name-node
> Affects Versions: 0.24.0, 0.23.3
> Reporter: Suresh Srinivas
> Assignee: Suresh Srinivas
> Attachments: MultipleSharedJournals.pdf, MultipleSharedJournals.pdf,
> MultipleSharedJournals.pdf
>
>
> Currently standby namenode relies on reading shared editlogs to stay current
> with the active namenode, for namespace changes. BackupNode used streaming
> edits from active namenode for doing the same. This jira is to explore using
> journal protocol based editlog streams for the standby namenode. A daemon in
> standby will get the editlogs from the active and write it to local edits. To
> begin with, the existing standby mechanism of reading from a file, will
> continue to be used, instead of from shared edits, from the local edits.
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