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From "Francis Liu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10569) Co-locate meta and master
Date Fri, 16 May 2014 11:22:50 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10569?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13998559#comment-13998559

Francis Liu commented on HBASE-10569:

I think the main motivation is the colocation of all the components that are usually involved
in a single "transaction". The 
main example of this is the Assignment, which involve: Master, META, ZooKeeper.
I see but the notion of consolidation is counter-intuitive if we want hbase to be horizontally
scalable. See the-node-that-must-not-be-named as an example.

#1 and #2 are part of a generic notification system, which will be used to propagate ACLs,
Visibility, Quotas. (In theory the base of this system is also the one behind the ZK-less
We should be able to implement a notification system without #1 and #2? Would be good to have
a doc describing and motivatiing why we need the dependency. And why it is better than a generic
version of the current approach.

For the Horizontal scalability, I think that we are going to have Multiple Master each one
operating on its subsection of "meta" (and the notification system). This means that you will
have concurrent assignments on different masters.
The best case is where you can fit a full table (regions metadata) on a single master, the
other case is where your table is split on multiple master which means that operation that
requires to work on the full set of regions e.g. delete, disable, enable need some sort of
coordination to provide the full consistency that you'll get with a full table that fits on
a single master.
Yep, instead avoiding distributed coordination tasks we should make distributed operations
a first class operation.

> Co-locate meta and master
> -------------------------
>                 Key: HBASE-10569
>                 URL: https://issues.apache.org/jira/browse/HBASE-10569
>             Project: HBase
>          Issue Type: Improvement
>          Components: master, Region Assignment
>            Reporter: Jimmy Xiang
>            Assignee: Jimmy Xiang
>             Fix For: 0.99.0
>         Attachments: Co-locateMetaAndMasterHBASE-10569.pdf, hbase-10569_v1.patch, hbase-10569_v2.patch,
hbase-10569_v3.1.patch, hbase-10569_v3.patch, master_rs.pdf
> I was thinking simplifying/improving the region assignments. The first step is to co-locate
the meta and the master as many people agreed on HBASE-5487.

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