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https://issues.apache.org/jira/browse/HDFS-7621?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14527189#comment-14527189
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Zhe Zhang commented on HDFS-7621:
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Thanks for working on this Walter.
bq. Balancer doesn't know EC Block group, it only know reported block( with
real blockId in datanode).
I'm not so sure about this. NameNode should only track striped block groups
instead of individual internal blocks. I also think you should be able to get
all internal block location when creating {{MovedBlocks#Locations}}. If that's
the case, the current code should already be able to avoid placing 2 striped
blocks in the same group on the same node. Maybe we can add a test first and
verify that from the debugging messages?
If the above is verified, the additional logic we need to take care of is to
avoid violating the rack properties of a striped block groups.
> Erasure Coding: update the Balancer/Mover data migration logic
> --------------------------------------------------------------
>
> Key: HDFS-7621
> URL: https://issues.apache.org/jira/browse/HDFS-7621
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Jing Zhao
> Assignee: Walter Su
> Attachments: HDFS-7621.001.patch
>
>
> Currently the Balancer/Mover only considers the distribution of replicas of
> the same block during data migration: the migration cannot decrease the
> number of racks. With EC the Balancer and Mover should also take into account
> the distribution of blocks belonging to the same block group.
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