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https://issues.apache.org/jira/browse/HDFS-9940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15198264#comment-15198264
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Tsz Wo Nicholas Sze commented on HDFS-9940:
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Thanks Yongjun for the note.  I agree that it should work.

Then, Balancer should only query the the DN conf but not change it.  It is fine 
if Balancer value <= DN value.  Otherwise, Balancer could warn the admin or 
throw an exception.  The admin could set the DN value using the reconfig 
command if desirable.  In this way, DNs are still protected.

> About abusing the cluster by Balancer, the balancer can only be run as admin 
> user "hdfs", right?

Admin sometime makes mistakes.  We should make it hard to make mistakes.

> Rename dfs.balancer.max.concurrent.moves to avoid confusion
> -----------------------------------------------------------
>
>                 Key: HDFS-9940
>                 URL: https://issues.apache.org/jira/browse/HDFS-9940
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: balancer & mover
>    Affects Versions: 2.6.0
>            Reporter: John Zhuge
>            Assignee: John Zhuge
>            Priority: Minor
>              Labels: supportability
>             Fix For: 2.8.0
>
>
> It is very confusing for both Balancer and Datanode to use the same property 
> {{dfs.datanode.balance.max.concurrent.moves}}. It is especially so for the 
> Balancer because the property has "datanode" in the name string. Many 
> customers forget to set the property for the Balancer.
> Change the Balancer to use a new property 
> {{dfs.balancer.max.concurrent.moves}}.



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