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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HDFS-988) saveNamespace can corrupt edits log
Date Mon, 26 Apr 2010 08:49:36 GMT

    [ https://issues.apache.org/jira/browse/HDFS-988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12860870#action_12860870
] 

dhruba borthakur commented on HDFS-988:
---------------------------------------

Hi todd, is it possible to make this one into the re-release of 0.21?

I do not think we should allow FSNamesystem.commitBlockSynchronization() in safe mode. Do
you visualize a case when this could cause a problem? I like it safer when I can say that
no new transactions can make it to the edits log when the namenode is in safemode.

> saveNamespace can corrupt edits log
> -----------------------------------
>
>                 Key: HDFS-988
>                 URL: https://issues.apache.org/jira/browse/HDFS-988
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>            Reporter: dhruba borthakur
>            Assignee: Todd Lipcon
>         Attachments: saveNamespace.txt
>
>
> The adminstrator puts the namenode is safemode and then issues the savenamespace command.
This can corrupt the edits log. The problem is that  when the NN enters safemode, there could
still be pending logSycs occuring from other threads. Now, the saveNamespace command, when
executed, would save a edits log with partial writes. I have seen this happen on 0.20.
> https://issues.apache.org/jira/browse/HDFS-909?focusedCommentId=12828853&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12828853

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