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https://issues.apache.org/jira/browse/HBASE-5487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13789874#comment-13789874
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Sergey Shelukhin commented on HBASE-5487:
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bq. We've tried putting state into zk. That failed. I really don't want to
put a whole bunch of new code into hbase that does almost exactly the same
thing as we currently have. It's going to fail.
As I said I don't think that is true. Our problem is not state being in ZK; it
is that the state is in multiple places in ZK itself for different parts of the
same region's state, plus some state in master to reconcile these, plus some
state that is not in ZK but only in master, plus also meta.
I.e. not the split between ZK and master but split logical state within both
and between them.
bq. Then you need a local cache if you want to make this performant at all
(That's how we got to the current state).
Our current state is not local cache, it's a bunch of actual state...
I am not yet sure how bad ZK-master split brain problem will be if ZK has
entire truth, let me think about it.
When you say no split-brain inside master, do you mean master will host the
meta and do all reads and writes to meta with no local intermediate state in
memory?
> Generic framework for Master-coordinated tasks
> ----------------------------------------------
>
> Key: HBASE-5487
> URL: https://issues.apache.org/jira/browse/HBASE-5487
> Project: HBase
> Issue Type: New Feature
> Components: master, regionserver, Zookeeper
> Affects Versions: 0.94.0
> Reporter: Mubarak Seyed
> Priority: Critical
> Attachments: Region management in Master.pdf
>
>
> Need a framework to execute master-coordinated tasks in a fault-tolerant
> manner.
> Master-coordinated tasks such as online-scheme change and delete-range
> (deleting region(s) based on start/end key) can make use of this framework.
> The advantages of framework are
> 1. Eliminate repeated code in Master, ZooKeeper tracker and Region-server for
> master-coordinated tasks
> 2. Ability to abstract the common functions across Master -> ZK and RS -> ZK
> 3. Easy to plugin new master-coordinated tasks without adding code to core
> components
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