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https://issues.apache.org/jira/browse/YARN-1029?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13850736#comment-13850736
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Bikas Saha commented on YARN-1029:
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I think we should be enable and verify ZKFC support for multiple reasons. ZKFC
is kind of standard in Hadoop HA and people are already using it. It will also
validate that people can hook up any external fencing agent (as long as it
talks HAServiceProtocol).
I took a quick look at the patch
1) I dont quite agree with the ZKFCProtocol being added to the AdminService.
The RM should have only 1 interface for HA related commands to be sent to it.
That interface is the HAServiceProtocol. External ZKFC or embedded elector or
the cluster admin. All of them should have the same entry point to the RM. I
dont think the RM should setup different protocols for the embedded elector
case.
2) there are a lot of new zk related options being added here which overlap
with the zkstore options. IMO, to make this really easy to use, we should be
offering zk-store and embedded leader election as a package. If ZKStore is used
then leader election can be embedded and the store is auto-fenced. If using
some other store, please use standard ZKFC which has fencing support to fence
the other RM/store. By doing this we get rid of fencing as a feature in
embedded leader election and we get rid of redundant ZK options. The elector
can just reuse the ZK options for the the store. This may also help reduce the
changes needed to embed the elector.
> Allow embedding leader election into the RM
> -------------------------------------------
>
> Key: YARN-1029
> URL: https://issues.apache.org/jira/browse/YARN-1029
> Project: Hadoop YARN
> Issue Type: Sub-task
> Reporter: Bikas Saha
> Assignee: Karthik Kambatla
> Attachments: embedded-zkfc-approach.patch, yarn-1029-0.patch,
> yarn-1029-0.patch, yarn-1029-approach.patch
>
>
> It should be possible to embed common ActiveStandyElector into the RM such
> that ZooKeeper based leader election and notification is in-built. In
> conjunction with a ZK state store, this configuration will be a simple
> deployment option.
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