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https://issues.apache.org/jira/browse/HADOOP-5189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12672070#action_12672070
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dhruba borthakur commented on HADOOP-5189:
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Hi Luca, Thanks for your comments. It would be nice if we can enhance the
current Namenode code to support invoking logSync() from multiple threads. This
will help namenode performance even when it is writing edits-log to multiple
files (and no bookKeeper is involed). If we have a patch for HADOOP-5188 and we
apply that first to the Hadoop trunk, then the bookKeeper patch will fit very
elegantly.
If the above is done as a pre-requisite for your bookKeeper patch, then we
would be able to support file based edits log as well as bookKeeper based
transaction log as the same time. This means that a namenode can log each
transactions to a local file as well as bookKeeper. This might help in
transitioning current hdfs namenode to using bookKeeper.
> it's more complex and not sure if it's worth the effort, in principle because
> you'd have to maintain two different logging system in parallel
I agree.
> Integration with BookKeeper logging system
> ------------------------------------------
>
> Key: HADOOP-5189
> URL: https://issues.apache.org/jira/browse/HADOOP-5189
> Project: Hadoop Core
> Issue Type: New Feature
> Affects Versions: 0.19.0
> Reporter: Luca Telloli
> Attachments: create.png, HADOOP-5189.patch
>
>
> BookKeeper is a system to reliably log streams of records
> (https://issues.apache.org/jira/browse/ZOOKEEPER-276). The NameNode is a
> natural target for such a system for being the metadata repository of the
> entire file system for HDFS.
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