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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-1981) When namenode goes down while checkpointing and if is started again subsequent Checkpointing is always failing
Date Wed, 25 May 2011 04:57:47 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1981?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13038957#comment-13038957
] 

ramkrishna.s.vasudevan commented on HDFS-1981:
----------------------------------------------

Writing UT for this may be difficult to reproduce the scenario.

The steps that I followed to reproduce this issue are
	1. Start namenode and backup namenode
	2. Allow checkpointing to happen such that the edits.new file is created on the namenode.
	3. At this point kill the NN and BNN.
	4. Now start the NN and BNN.
	5. When checkpointing starts again we will get the above exception.


The exact problem comes in the loadFSEdits() api in  FSImage.java

Here if the loadFSEdits() api returns 0 then 

if (fsImage.recoverTransitionRead(dataDirs, editsDirs, startOpt)) {
          fsImage.saveNamespace(true);
}

saveNamespace() will not be invoked.

Kindly correct me if you find any problems in this.



> When namenode goes down while checkpointing and if is started again subsequent Checkpointing
is always failing
> --------------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-1981
>                 URL: https://issues.apache.org/jira/browse/HDFS-1981
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>    Affects Versions: 0.23.0
>         Environment: Linux
>            Reporter: ramkrishna.s.vasudevan
>             Fix For: 0.23.0
>
>
> This scenario is applicable in NN and BNN case.
> When the namenode goes down after creating the edits.new, on subsequent restart the divertFileStreams
will not happen to edits.new as the edits.new file is already present and the size is zero.
> so on trying to saveCheckPoint an exception occurs 
> 2011-05-23 16:38:57,476 WARN org.mortbay.log: /getimage: java.io.IOException: GetImage
failed. java.io.IOException: Namenode has an edit log with timestamp of 2011-05-23 16:38:56
but new checkpoint was created using editlog  with timestamp 2011-05-23 16:37:30. Checkpoint
Aborted.
> This is a bug or is that the behaviour.

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