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https://issues.apache.org/jira/browse/HDFS-3570?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14635450#comment-14635450
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Hadoop QA commented on HDFS-3570:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:red}-1{color} | patch |   0m  0s | The patch command could not apply 
the patch during dryrun. |
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|| Subsystem || Report/Notes ||
| Patch URL | 
http://issues.apache.org/jira/secure/attachment/12627311/HDFS-3570.2.patch |
| Optional Tests | site javadoc javac unit findbugs checkstyle |
| git revision | trunk / 3b7ffc4 |
| Console output | 
https://builds.apache.org/job/PreCommit-HDFS-Build/11771/console |


This message was automatically generated.

> Balancer shouldn't rely on "DFS Space Used %" as that ignores non-DFS used 
> space
> --------------------------------------------------------------------------------
>
>                 Key: HDFS-3570
>                 URL: https://issues.apache.org/jira/browse/HDFS-3570
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: balancer & mover
>    Affects Versions: 2.0.0-alpha
>            Reporter: Harsh J
>            Assignee: Akira AJISAKA
>            Priority: Minor
>         Attachments: HDFS-3570.2.patch, HDFS-3570.aash.1.patch
>
>
> Report from a user here: 
> https://groups.google.com/a/cloudera.org/d/msg/cdh-user/pIhNyDVxdVY/b7ENZmEvBjIJ,
>  post archived at http://pastebin.com/eVFkk0A0
> This user had a specific DN that had a large non-DFS usage among 
> dfs.data.dirs, and very little DFS usage (which is computed against total 
> possible capacity). 
> Balancer apparently only looks at the usage, and ignores to consider that 
> non-DFS usage may also be high on a DN/cluster. Hence, it thinks that if a 
> DFS Usage report from DN is 8% only, its got a lot of free space to write 
> more blocks, when that isn't true as shown by the case of this user. It went 
> on scheduling writes to the DN to balance it out, but the DN simply can't 
> accept any more blocks as a result of its disks' state.
> I think it would be better if we _computed_ the actual utilization based on 
> {{(100-(actual remaining space))/(capacity)}}, as opposed to the current 
> {{(dfs used)/(capacity)}}. Thoughts?
> This isn't very critical, however, cause it is very rare to see DN space 
> being used for non DN data, but it does expose a valid bug.



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