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Date: Wed, 16 Mar 2016 19:15:33 +0000 (UTC)
From: "Vinod Kumar Vavilapalli (JIRA)" <jira@apache.org>
To: yarn-issues@hadoop.apache.org
Message-ID: <JIRA.12758944.1417540069000.39662.1458155733957@Atlassian.JIRA>
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Subject: [jira] [Commented] (YARN-2915) Enable YARN RM scale out via
 federation using multiple RM's
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    [ https://issues.apache.org/jira/browse/YARN-2915?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15197956#comment-15197956 ] 

Vinod Kumar Vavilapalli commented on YARN-2915:
-----------------------------------------------

One thing that occurred to me in an offline conversation with [~subru] and [~leftnoteasy] is about the modeling of queues and their shares in different sub-clusters.

As seems to be already proposed, it is very desirable to have a unified *logic queues* that are applicable across all sub-clusters.

With unified logical queues, looks like there are some proposals for ways of how resources can get sub-divided amongst different sub-clusters. But to me, they already map to an existing concept in YARN - *Node Partitions* / node-labels !

Essentially you have *one YARN cluster* -> *multiple sub-clusters* -> *each sub-cluster with multiple node-partitions*. This can further be extended to more levels. For e.g. we can unify rack also under the same concept.

The advantage of unifying this with node-partitions is that we can have
 - one single administrative view philosophy of sub-clusters, node-partitions, racks etc
 - unified configuration mechanisms: Today we support centralized and distributed node-partition mechanisms, exclusive / non-exclusive access etc.
 - unified queue-sharing models - today we already can assign X% of a node-partition to a queue. This way we can, again, reuse existing concepts, mental models and allocation policies - instead of creating specific policies for sub-cluster sharing like the user-based share that is proposed.

We will have to dig deeper into the details, but it seems to me that node-partition and sub-cluster are equivalence classes except for the fact that two sub-clusters report to two different RMs (physically / implementation wise) which isn't the case today with node-partitions.

Thoughts? /cc [~curino] [~chris.douglas]

> Enable YARN RM scale out via federation using multiple RM's
> -----------------------------------------------------------
>
>                 Key: YARN-2915
>                 URL: https://issues.apache.org/jira/browse/YARN-2915
>             Project: Hadoop YARN
>          Issue Type: New Feature
>          Components: nodemanager, resourcemanager
>            Reporter: Sriram Rao
>            Assignee: Subru Krishnan
>         Attachments: FEDERATION_CAPACITY_ALLOCATION_JIRA.pdf, Federation-BoF.pdf, Yarn_federation_design_v1.pdf, federation-prototype.patch
>
>
> This is an umbrella JIRA that proposes to scale out YARN to support large clusters comprising of tens of thousands of nodes.   That is, rather than limiting a YARN managed cluster to about 4k in size, the proposal is to enable the YARN managed cluster to be elastically scalable.  


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