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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HDFS-988) saveNamespace can corrupt edits log
Date Fri, 19 Feb 2010 22:50:27 GMT

    [ https://issues.apache.org/jira/browse/HDFS-988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12836021#action_12836021
] 

Todd Lipcon commented on HDFS-988:
----------------------------------

Hi Dhruba,

I still think we should fix this in the other issues and then backport to 20. But I'll do
a review of this patch here since you've already uploaded it:

- in setPermission, the audit logging has moved outside the synchronized block. Thus dir.getFileInfo
may actually return incorrect info (or even fail if it races with someone deleting the file)
- same goes for setOwner
- I think it's OK, but can you verify that the top synchronized block in getAdditionalBlock
can never have side effects? I don't know the lease management code well enough - checkLease
is guaranteed side-effect free?



> 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
>         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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