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From "Uma Maheswara Rao G (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-2975) Rename with overwrite flag true can make NameNode to stuck in safemode on NN (crash + restart).
Date Tue, 02 Sep 2014 15:53:22 GMT

    [ https://issues.apache.org/jira/browse/HDFS-2975?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14118283#comment-14118283
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Uma Maheswara Rao G commented on HDFS-2975:
-------------------------------------------

Yi,  Thanks a lot for the explanation.
+1 on the patch. [~vinayrpet], Do you have any comments?

> Rename with overwrite flag true can make NameNode to stuck in safemode on NN (crash +
restart).
> -----------------------------------------------------------------------------------------------
>
>                 Key: HDFS-2975
>                 URL: https://issues.apache.org/jira/browse/HDFS-2975
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>            Reporter: Uma Maheswara Rao G
>            Assignee: Uma Maheswara Rao G
>         Attachments: HDFS-2975.001.patch
>
>
> When we rename the file with overwrite flag as true, it will delete the destination file
blocks. After deleting the blocks, whenever it releases the fsNameSystem lock, NN can give
the invalidation work to corresponding DNs to delete the blocks.
> Parallaly it will sync the rename related edits to editlog file. At this step before
NN sync the edits if NN crashes, NN can stuck into safemode on restart. This is because block
already deleted from the DN as part of invalidations. But dst file still exist as rename edits
not persisted in log file and no DN will report that blocks now.
> This is similar to HDFS-2815
>  



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