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https://issues.apache.org/jira/browse/HDFS-5177?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vinay updated HDFS-5177:
------------------------

    Assignee: Vinay
      Status: Patch Available  (was: Open)
    
> blocksScheduled  count should be decremented for abandoned blocks
> -----------------------------------------------------------------
>
>                 Key: HDFS-5177
>                 URL: https://issues.apache.org/jira/browse/HDFS-5177
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 2.1.0-beta, 3.0.0
>            Reporter: Vinay
>            Assignee: Vinay
>         Attachments: HDFS-5177.patch
>
>
> DatanodeDescriptor#incBlocksScheduled() will be called for all datanodes of 
> the block on each allocation. But same should be decremented for abandoned 
> blocks.
> When one of the datanodes is down and same is allocated for the block along 
> with other live datanodes, then this block will be abandoned, but the 
> scheduled count on other datanodes will consider live datanodes as loaded, 
> but in reality these datanodes may not be loaded.
> Anyway this scheduled count will be rolled every 20 mins.
> Problem will come if the rate of creation of files is more. Due to increase 
> in the scheduled count, there might be chances of missing local datanode to 
> write to. and some times writes also can fail in small clusters.
> So we need to decrement the unnecessary count on abandon block call.

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