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https://issues.apache.org/jira/browse/HDFS-6821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14089671#comment-14089671
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Samer Al-Kiswany commented on HDFS-6821:
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I see.
Thanks Chris.
-samer
> Atomicity of multi file operations
> ----------------------------------
>
> Key: HDFS-6821
> URL: https://issues.apache.org/jira/browse/HDFS-6821
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Samer Al-Kiswany
> Priority: Minor
>
> Looking how HDFS updates the log files in case of chmod –r or chown –r
> operations. In these operations, HDFS name node seems to update each file
> separately; consequently the strace of the operation looks as follows.
> append(edits)
> fsync(edits)
> append(edits)
> fsync(edits)
> -----------------------
> append(edits)
> fsync(edits)
> append(edits)
> fsync(edits)
> If a crash happens in the middle of this operation (e.g. at the dashed line
> in the trace), the system will end up with part of the files updates with the
> new owner or permissions and part still with the old owner.
> Isn’t it better to log the whole operations (chown -r) as one entry in the
> edit file?
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