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https://issues.apache.org/jira/browse/HDFS-988?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matt Foley updated HDFS-988:
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Attachment: HDFS-988_fix_synchs.patch
Here is an extract from some other stuff I've been working on, that addresses
the sync issue for calls into SafeMode methods. It avoids taking the r/w lock
for fast read-only operations, where it seems to me it can be made safe with a
lighter-weight mechanism.
This patch does not address the need Todd observed to add r/w lock to
- getNamespaceInfo
- setQuota
- renewLease
- nextGenerationStamp
> 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
> Affects Versions: 0.20-append, 0.21.0, 0.22.0
> Reporter: dhruba borthakur
> Assignee: Todd Lipcon
> Priority: Blocker
> Fix For: 0.20-append, 0.22.0
>
> Attachments: HDFS-988_fix_synchs.patch, hdfs-988-2.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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