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https://issues.apache.org/jira/browse/HADOOP-6450?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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dhruba borthakur updated HADOOP-6450:
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    Status: Patch Available  (was: Open)

Can somebody please review this patch?

> Enhance FSDataOutputStream to allow retrieving the current number of replicas 
> of current block
> ----------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-6450
>                 URL: https://issues.apache.org/jira/browse/HADOOP-6450
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: fs
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>         Attachments: Replicable.txt, Replicable.txt
>
>
> The current HDFS implementation has the limitation that it does not replicate 
> the last partial block of a file when it is being written into until the file 
> is closed. There are some long running applications (e.g. HBase) which writes 
> transactions logs into HDFS. If datanode(s) in the write pipeline dies off, 
> the application has no knowledge of it until all the datanode(s) fail and the 
> application gets an IO error.
> These applictions would benefit a lot if they can determine the number of 
> live replicas of the current block to which it is writing data. For example, 
> the application can decide that when one of the datanode in the write 
> pipeline fails it will close the file and start writing to  a new file.

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