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https://issues.apache.org/jira/browse/HDFS-14349?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16795553#comment-16795553
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star edited comment on HDFS-14349 at 5/2/19 3:41 PM:
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It has been verified that edit log roll will be triggered by multiple SNN.
I‘ve proposed a improvement issue HDFS-14378 to put things right once and for
all. The main idea is to make ANN rolling its edit log and download fsimage
randomly from one SNN. SNN will just do checkpointing and tail editlogs. You
are welcome to make a review or make contributions.
was (Author: starphin):
Yes, it seems that normal edit log roll will be triggered by multiple SNN. I am
doing unit tests to verify the action.
> Edit log may be rolled more frequently than necessary with multiple Standby
> nodes
> ---------------------------------------------------------------------------------
>
> Key: HDFS-14349
> URL: https://issues.apache.org/jira/browse/HDFS-14349
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: ha, hdfs, qjm
> Reporter: Erik Krogen
> Assignee: Ekanth Sethuramalingam
> Priority: Major
>
> When HDFS-14317 was fixed, we tackled the problem that in a cluster with
> in-progress edit log tailing enabled, a Standby NameNode may _never_ roll the
> edit logs, which can eventually cause data loss.
> Unfortunately, in the process, it was made so that if there are multiple
> Standby NameNodes, they will all roll the edit logs at their specified
> frequency, so the edit log will be rolled X times more frequently than they
> should be (where X is the number of Standby NNs). This is not as bad as the
> original bug since rolling frequently does not affect correctness or data
> availability, but may degrade performance by creating more edit log segments
> than necessary.
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