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From "Suresh Srinivas (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-2354) Generalize the HAServiceProtocol interface
Date Tue, 25 Oct 2011 16:34:32 GMT

    [ https://issues.apache.org/jira/browse/HDFS-2354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13135205#comment-13135205

Suresh Srinivas commented on HDFS-2354:

bq. The implementation in HDFS-1974 has the drawback that Namenode / NamenodeRpcServer implements
HAServiceProtocol, which is against the goal of HDFS-1623 to build a framework for HA.

Can you explain hot it is against the goal of HDFS-1623? I think you may be misunderstanding
HAServiceProtocol's intent. HAServiceProtocol allows Namenode to be treated as a resource.
Whether it is CRM+LRM from Linux HA or FailoverController, both need this. This is irrespective
of where FailoverController sits - as a separate daemon or a module inside the namenode process.

I have been very confused by neutral state and how it avoids the need for fencing. If you
create a detailed write up on this aspect, I am willing to spend some time on that.
> Generalize the HAServiceProtocol interface
> ------------------------------------------
>                 Key: HDFS-2354
>                 URL: https://issues.apache.org/jira/browse/HDFS-2354
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: name-node
>            Reporter: Justin Joseph
>            Assignee: Justin Joseph
>         Attachments: HAService_fw_Class_Diagram.JPG, HDFS-2354.1.patch, HDFS-2354.patch
> This JIRA intends to revisit the patches committed for HADOOP-7455 and HDFS-1974 &
to provide more generic interfaces which allows alternative HA implementations to co-exist
complying with HAServiceProtocol.
> Some of the considerations are
> 1) Support life cycle methods (start*() and stop() APIs) in HAServiceProtocol
> 2) Support custom states in HAServiceProtocol
> 3) As per the patch submitted for HDFS-1974, Namenode implements HAService interface.
This needs to be reconsidered.
> I will elaborate on these points, in the form of comments below.

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