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https://issues.apache.org/jira/browse/HDFS-3077?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13245847#comment-13245847
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Suresh Srinivas commented on HDFS-3077:
---------------------------------------

bq. How can step 3 in section 2.4 be completed independent of quorum? Step 4 
indicates that it requires a quorum of nodes to respond successfully to the 
newEpoch message. Here's an example:
What I meant was at each JN, step 3 completes. Hence the example Hari was 
giving.
                
> 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, 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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