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https://issues.apache.org/jira/browse/HDFS-3077?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13407684#comment-13407684
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Suresh Srinivas commented on HDFS-3077:
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Todd, I have not had time to look into the comments or the patch. Will try to
get this done in next few days.
As I said earlier, keeping JournalProtocol without adding Quorum semantics
allows writers that have different policy. Perhaps the protocols should be
different and may be JournalProtocol from 3092 can remain as is. Again this is
an early thought - will spend time on this in next few days.
Quick comment:
bq. I disagree with this statement. The commit protocol is strongly intertwined
with the way in which the server has to behave. For example, the "new epoch"
command needs to provide back certain information about the current state of
the journals and previous paxos-style 'accepted' decisions. Trying to shoehorn
it into a generic protocol doesn't make much sense to me.
What do you mean by "paxos-style". How does it relate to ZAB?
> Quorum-based protocol for reading and writing edit logs
> -------------------------------------------------------
>
> Key: HDFS-3077
> URL: https://issues.apache.org/jira/browse/HDFS-3077
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: ha, name-node
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Attachments: hdfs-3077-partial.txt, hdfs-3077.txt, hdfs-3077.txt,
> qjournal-design.pdf, qjournal-design.pdf
>
>
> Currently, one of the weak points of the HA design is that it relies on
> shared storage such as an NFS filer for the shared edit log. One alternative
> that has been proposed is to depend on BookKeeper, a ZooKeeper subproject
> which provides a highly available replicated edit log on commodity hardware.
> This JIRA is to implement another alternative, based on a quorum commit
> protocol, integrated more tightly in HDFS and with the requirements driven
> only by HDFS's needs rather than more generic use cases. More details to
> follow.
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