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From "Arpit Agarwal (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-10301) BlockReport retransmissions may lead to storages falsely being declared zombie if storage report processing happens out of order
Date Tue, 27 Sep 2016 03:51:21 GMT

    [ https://issues.apache.org/jira/browse/HDFS-10301?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15524968#comment-15524968
] 

Arpit Agarwal commented on HDFS-10301:
--------------------------------------

bq.  As all storage reports in the single RPC BR satisfy the condition that triggers removal
of the lease, all storage reports after the first storage report will be ignored without the
change.
Isn't that because the patch also removes the lastStorageInRpc check? If that check was not
removed then the workaround wouldn't be necessary.

bq. When BRs are split into multiple RPCS: Say 2 BRs from the same DN are processed at the
same time.
We should make a more resilient fix that doesn't require the lease ID workaround. In the interests
of making forward progress, can we just remove the zombie processing for now and fix the other
issues separately?

> 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
>         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-10301.013.patch,
HDFS-10301.014.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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