[jira] [Commented] (HDFS-5958) One very large node in a cluster prevents balancer from balancing data

["Tsz Wo Nicholas Sze (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-5958?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14643750#comment-14643750 ] 

Tsz Wo Nicholas Sze commented on HDFS-5958:
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> ...  in my case I had a 20% utilized box, a few 80-90% utilized ones and that huge 4% utilized machine, ...

In this case, Balancer should move blocks from the 80-90% utilized machines to the other machines.  No?

> One very large node in a cluster prevents balancer from balancing data
> ----------------------------------------------------------------------
>
>                 Key: HDFS-5958
>                 URL: https://issues.apache.org/jira/browse/HDFS-5958
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: balancer & mover
>    Affects Versions: 2.2.0
>         Environment: Hadoop cluster with 4 nodes: 3 with 500Gb drives and one with 4Tb drive.
>            Reporter: Alexey Kovyrin
>
> In a cluster with a set of small nodes and one much larger node balancer always selects the large node as the target even though it already has a copy of each block in the cluster.
> This causes the balancer to enter an infinite loop and stop balancing other nodes because each balancing iteration selects the same target and then could not find a single block to move.



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