[jira] Commented: (HBASE-2896) Retain assignment information between cluster shutdown/startup

["HBase Review Board (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-2896?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12929220#action_12929220 ] 

HBase Review Board commented on HBASE-2896:
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Message from: "Jonathan Gray" <jg...@apache.org>

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http://review.cloudera.org/r/1186/
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Review request for hbase, stack and khemani.


Summary
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Adds a configuration option (default true in this patch) for retaining assignment on startup.  If true, initial assignment plan attempts to use existing assignment info from META (we don't delete assignment info in META when RS closes region).

Also changes initial assignment to skip regions from disabled tables rather than looking at offline flag.


This addresses bug HBASE-2896.
    http://issues.apache.org/jira/browse/HBASE-2896


Diffs
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  trunk/src/main/java/org/apache/hadoop/hbase/catalog/MetaReader.java 1032133 
  trunk/src/main/java/org/apache/hadoop/hbase/master/AssignmentManager.java 1032133 
  trunk/src/main/java/org/apache/hadoop/hbase/master/LoadBalancer.java 1032133 
  trunk/src/test/java/org/apache/hadoop/hbase/master/TestLoadBalancer.java 1032133 

Diff: http://review.cloudera.org/r/1186/diff


Testing
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I will write a new unit test of the load balancing method to make sure it does what is expected.

I could write a cluster-level TestRetainAssignment test which actually tests it works end to end but I'm not sure it's necessary.  Could also add some modification to TestClusterRestart or whatever that one is.


Thanks,

Jonathan




> Retain assignment information between cluster shutdown/startup
> --------------------------------------------------------------
>
>                 Key: HBASE-2896
>                 URL: https://issues.apache.org/jira/browse/HBASE-2896
>             Project: HBase
>          Issue Type: New Feature
>          Components: master, regionserver
>            Reporter: Jonathan Gray
>            Assignee: Jonathan Gray
>             Fix For: 0.92.0
>
>
> Over in HBASE-57 we want to consider block locations for region assignment.  This is most important during cluster startup where you currently lose all locality because regions are assignment randomly.
> This jira is about a shot-term solution to the cluster startup problem by retaining assignment information after a cluster shutdown and using it on the next cluster startup.

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