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https://issues.apache.org/jira/browse/HDFS-14378?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16925642#comment-16925642
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Hadoop QA commented on HDFS-14378:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue} 0m
0s{color} | {color:blue} Docker mode activated. {color} |
| {color:red}-1{color} | {color:red} patch {color} | {color:red} 0m 7s{color}
| {color:red} HDFS-14378 does not apply to trunk. Rebase required? Wrong
Branch? See https://wiki.apache.org/hadoop/HowToContribute for help. {color} |
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|| Subsystem || Report/Notes ||
| JIRA Issue | HDFS-14378 |
| JIRA Patch URL |
https://issues.apache.org/jira/secure/attachment/12966476/HDFS-14378-trunk.006.patch
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| Console output |
https://builds.apache.org/job/PreCommit-HDFS-Build/27825/console |
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> Simplify the design of multiple NN and both logic of edit log roll and
> checkpoint
> ---------------------------------------------------------------------------------
>
> Key: HDFS-14378
> URL: https://issues.apache.org/jira/browse/HDFS-14378
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: ha, namenode
> Affects Versions: 3.1.2
> Reporter: star
> Assignee: star
> Priority: Major
> Attachments: HDFS-14378-trunk.001.patch, HDFS-14378-trunk.002.patch,
> HDFS-14378-trunk.003.patch, HDFS-14378-trunk.004.patch,
> HDFS-14378-trunk.005.patch, HDFS-14378-trunk.006.patch
>
>
> HDFS-6440 introduced a mechanism to support more than 2 NNs. It
> implements a first-writer-win policy to avoid duplicated fsimage downloading.
> Variable 'isPrimaryCheckPointer' is used to hold the first-writer state, with
> which SNN will provide fsimage for ANN next time. Then we have three roles in
> NN cluster: ANN, one primary SNN, one or more normal SNN.
> Since HDFS-12248, there may be more than two primary SNN shortly after
> a exception occurred. It takes care with a scenario that SNN will not upload
> fsimage on IOE and Interrupted exceptions. Though it will not cause any
> further functional issues, it is inconsistent.
> Futher more, edit log may be rolled more frequently than necessary with
> multiple Standby name nodes, HDFS-14349. (I'm not so sure about this, will
> verify by unit tests or any one could point it out.)
> Above all, I‘m wondering if we could make it simple with following
> changes:
> * There are only two roles:ANN, SNN
> * ANN will roll its edit log every DFS_HA_LOGROLL_PERIOD_KEY period.
> * ANN will select a SNN to download checkpoint.
> SNN will just do logtail and checkpoint. Then provide a servlet for fsimage
> downloading as normal. SNN will not try to roll edit log or send checkpoint
> request to ANN.
> In a word, ANN will be more active. Suggestions are welcomed.
>
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