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https://issues.apache.org/jira/browse/HDFS-13573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16480077#comment-16480077
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Hudson commented on HDFS-13573:
-------------------------------

SUCCESS: Integrated in Jenkins build Hadoop-trunk-Commit #14234 (See 
[https://builds.apache.org/job/Hadoop-trunk-Commit/14234/])
HDFS-13573. Javadoc for BlockPlacementPolicyDefault is inaccurate. (yqlin: rev 
f749517cc78fc761cecff21e8b7f65fb719bfca2)
* (edit) 
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java


> Javadoc for BlockPlacementPolicyDefault is inaccurate
> -----------------------------------------------------
>
>                 Key: HDFS-13573
>                 URL: https://issues.apache.org/jira/browse/HDFS-13573
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 3.1.0
>            Reporter: Yiqun Lin
>            Assignee: Zsolt Venczel
>            Priority: Trivial
>         Attachments: HDFS-13573.01.patch, HDFS-13573.02.patch
>
>
> Current rule of default block placement policy:
> {quote}The replica placement strategy is that if the writer is on a datanode,
>  the 1st replica is placed on the local machine,
>  otherwise a random datanode. The 2nd replica is placed on a datanode
>  that is on a different rack. The 3rd replica is placed on a datanode
>  which is on a different node of the rack as the second replica.
> {quote}
> *if the writer is on a datanode, the 1st replica is placed on the local 
> machine*, actually this can be decided by the hdfs client. The client can 
> pass {{CreateFlag#NO_LOCAL_WRITE}} that request to not put a block replica on 
> the local datanode. But subsequent replicas will still follow default block 
> placement policy.



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