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https://issues.apache.org/jira/browse/HDFS-10301?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15402951#comment-15402951
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Daryn Sharp commented on HDFS-10301:
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I've read this jira as I said I would, and I've looked at the patch.
Our nightly build & deploy for 2.7 is broken. DNs claim to report thousands of
blocks, NN says nope, -1. This should be reason enough to revert until we get
to the bottom of it. We're reverting internally. If that fixes it, I will
have someone help me revert tomorrow morning if not already.
Why is this patch changing per-storage reports when it's the single-rpc report
that is the problem? Is this change compatible?
# What does an old NN do if it gets this pseudo-report? Will it forget about
all the blocks on the non-last storage?
# What does a new NN do when it gets old style reports? Will it remove all but
the last storage?
This zombie detection, report context, etc is getting out of hand. I don't
understand why the zombie detection isn't based on the healthy storages in the
heartbeat. Anything else gets flagged as failed and the heartbeat monitor
disposes of them.
> BlockReport retransmissions may lead to storages falsely being declared
> zombie if storage report processing happens out of order
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-10301
> URL: https://issues.apache.org/jira/browse/HDFS-10301
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.6.1
> Reporter: Konstantin Shvachko
> Assignee: Vinitha Reddy Gankidi
> Priority: Critical
> Fix For: 2.7.4
>
> Attachments: HDFS-10301.002.patch, HDFS-10301.003.patch,
> HDFS-10301.004.patch, HDFS-10301.005.patch, HDFS-10301.006.patch,
> HDFS-10301.007.patch, HDFS-10301.008.patch, HDFS-10301.009.patch,
> HDFS-10301.01.patch, HDFS-10301.010.patch, HDFS-10301.011.patch,
> HDFS-10301.012.patch, HDFS-10301.branch-2.7.patch, HDFS-10301.branch-2.patch,
> HDFS-10301.sample.patch, zombieStorageLogs.rtf
>
>
> When NameNode is busy a DataNode can timeout sending a block report. Then it
> sends the block report again. Then NameNode while process these two reports
> at the same time can interleave processing storages from different reports.
> This screws up the blockReportId field, which makes NameNode think that some
> storages are zombie. Replicas from zombie storages are immediately removed,
> causing missing blocks.
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