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From "Ming Ma (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-6425) Large postponedMisreplicatedBlocks has impact on blockReport latency
Date Mon, 04 Aug 2014 19:28:12 GMT

     [ https://issues.apache.org/jira/browse/HDFS-6425?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Ming Ma updated HDFS-6425:
--------------------------

    Status: Patch Available  (was: Open)

> Large postponedMisreplicatedBlocks has impact on blockReport latency
> --------------------------------------------------------------------
>
>                 Key: HDFS-6425
>                 URL: https://issues.apache.org/jira/browse/HDFS-6425
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Ming Ma
>            Assignee: Ming Ma
>         Attachments: HDFS-6425-Test-Case.pdf, HDFS-6425.patch
>
>
> Sometimes we have large number of over replicates when NN fails over. When the new active
NN took over, over replicated blocks will be put to postponedMisreplicatedBlocks until all
DNs for that block aren't stale anymore.
> We have a case where NNs flip flop. Before postponedMisreplicatedBlocks became empty,
NN fail over again and again. So postponedMisreplicatedBlocks just kept increasing until the
cluster is stable. 
> In addition, large postponedMisreplicatedBlocks could make rescanPostponedMisreplicatedBlocks
slow. rescanPostponedMisreplicatedBlocks takes write lock. So it could slow down the block
report processing.



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