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https://issues.apache.org/jira/browse/HDFS-1172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13104770#comment-13104770
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Todd Lipcon commented on HDFS-1172:
-----------------------------------
Hi Ravi. I think you're right, good catch. I spent some time yesterday working
on writing a test that shows this bug, since the existing ones clearly don't do
enough coverage. I'll upload something new soon.
> Blocks in newly completed files are considered under-replicated too quickly
> ---------------------------------------------------------------------------
>
> Key: HDFS-1172
> URL: https://issues.apache.org/jira/browse/HDFS-1172
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: name-node
> Affects Versions: 0.21.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Fix For: 0.22.0, 0.23.0
>
> Attachments: HDFS-1172.patch, hdfs-1172.txt,
> replicateBlocksFUC.patch, replicateBlocksFUC1.patch, replicateBlocksFUC1.patch
>
>
> I've seen this for a long time, and imagine it's a known issue, but couldn't
> find an existing JIRA. It often happens that we see the NN schedule
> replication on the last block of files very quickly after they're completed,
> before the other DNs in the pipeline have a chance to report the new block.
> This results in a lot of extra replication work on the cluster, as we
> replicate the block and then end up with multiple excess replicas which are
> very quickly deleted.
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