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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-1779) After NameNode restart , Clients can not read partial files even after client invokes Sync.
Date Fri, 20 May 2011 19:18:47 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1779?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13037012#comment-13037012
] 

dhruba borthakur commented on HDFS-1779:
----------------------------------------

if the namenode restarts, the datanode should invoke FSDataSet.recoverBlocksBeingWritten().
This will send all blocks in the block being written directory to the NN.



> After NameNode restart , Clients can not read partial files even after client invokes
Sync.
> -------------------------------------------------------------------------------------------
>
>                 Key: HDFS-1779
>                 URL: https://issues.apache.org/jira/browse/HDFS-1779
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: data-node, name-node
>    Affects Versions: 0.20-append
>         Environment: Linux
>            Reporter: Uma Maheswara Rao G
>            Assignee: Uma Maheswara Rao G
>             Fix For: 0.20-append
>
>         Attachments: HDFS-1779.patch
>
>
> In Append HDFS-200 issue,
> If file has 10 blocks and after writing 5 blocks if client invokes sync method then NN
will persist the blocks information in edits. 
> After this if we restart the NN, All the DataNodes will reregister with NN. But DataNodes
are not sending the blocks being written information to NN. DNs are sending the blocksBeingWritten
information in DN startup. So, here NameNode can not find that the 5 persisted blocks belongs
to which datanodes. This information can build based on block reports from DN. Otherwise we
will loose this 5 blocks information even NN persisted that block information in edits. 

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