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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-5724) Datanode should report deletion of blocks to Namenode explicitly
Date Sun, 10 May 2009 10:09:45 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-5724?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12707770#action_12707770
] 

dhruba borthakur commented on HADOOP-5724:
------------------------------------------

This is mostly a case of cleaning up space in the datanode(s) right? In the current code,
the NN removes the block from te blockmap before sending the delete request to the datanode(s)...
essentially assuming that the block will be successfully deleted in the datanode, isn't it?
Are you seeing any practical cases when this existing approach is inadequate?

> Datanode should report deletion of blocks to Namenode explicitly
> ----------------------------------------------------------------
>
>                 Key: HADOOP-5724
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5724
>             Project: Hadoop Core
>          Issue Type: Bug
>            Reporter: Suresh Srinivas
>            Assignee: Suresh Srinivas
>             Fix For: 0.21.0
>
>         Attachments: blockdel.patch, blockdel.patch
>
>
> Currently datanode notifies namenode newly added blocks and the blocks that are corrupt.
There is no explicit message from the datanode to the namenode to indicate the deletion of
blocks. Block reports from the datanode is the only way for the namenode to learn about the
deletion of blocks at a datanode. With the addition of explicit request to indicate to block
deletion, block report interval (which is currently 1 hour) can be increased to a longer duration.
This reduces load on both namenode and datanodes.
>  

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