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Date: Sun, 12 Jun 2011 03:45:52 +0000 (UTC)
From: "Todd Lipcon (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
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Subject: [jira] [Commented] (HDFS-988) saveNamespace can corrupt edits log,
 apparently due to race conditions
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    [ https://issues.apache.org/jira/browse/HDFS-988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13048215#comment-13048215 ] 

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

+1 on the trunk patch, once you've run the full test suite through jcarder (with the "lockclasses" branch that detects rwlock issues). Also looks like it needs a rebase

> saveNamespace can corrupt edits log, apparently due to race conditions
> ----------------------------------------------------------------------
>
>                 Key: HDFS-988
>                 URL: https://issues.apache.org/jira/browse/HDFS-988
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>    Affects Versions: 0.20-append, 0.21.0, 0.22.0
>            Reporter: dhruba borthakur
>            Assignee: Eli Collins
>            Priority: Blocker
>             Fix For: 0.20-append, 0.22.0
>
>         Attachments: 988-fixups.txt, HDFS-988_fix_synchs.patch, hdfs-988-2.patch, hdfs-988-3.patch, hdfs-988-4.patch, hdfs-988-5.patch, hdfs-988-6.patch, hdfs-988-b22-1.patch, hdfs-988.txt, saveNamespace.txt, saveNamespace_20-append.patch
>
>
> 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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