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https://issues.apache.org/jira/browse/HBASE-18946?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16276483#comment-16276483
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ramkrishna.s.vasudevan commented on HBASE-18946:
------------------------------------------------
bq.But the problem is no longer we call roundrobinAssignment from LB instead we
will call retainAssignment() only. This happens only when replicas are created
I said this because now we set the target server so the round robin logic is
not with the AM. Generally AM decides if the assignment shouldbe round robin or
retain assignment. So here it is always retain assignment.
As I said LB knows about replica and it does the replica assignment pretty well
but that is when it has the entire cluster available. During the course of
assignment it cannot make a judgement on it. I don't find any other simple way
to make LB aware of it unless some where we need a grouping of the regions to
be assigned. So are you ok with patch for commit [~saint....@gmail.com]?
> Stochastic load balancer assigns replica regions to the same RS
> ---------------------------------------------------------------
>
> Key: HBASE-18946
> URL: https://issues.apache.org/jira/browse/HBASE-18946
> Project: HBase
> Issue Type: Bug
> Affects Versions: 2.0.0-alpha-3
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
> Fix For: 2.0.0-beta-1
>
> Attachments: HBASE-18946.patch, HBASE-18946.patch,
> HBASE-18946_2.patch, HBASE-18946_2.patch, HBASE-18946_simple_7.patch,
> HBASE-18946_simple_8.patch, TestRegionReplicasWithRestartScenarios.java
>
>
> Trying out region replica and its assignment I can see that some times the
> default LB Stocahstic load balancer assigns replica regions to the same RS.
> This happens when we have 3 RS checked in and we have a table with 3
> replicas. When a RS goes down then the replicas being assigned to same RS is
> acceptable but the case when we have enough RS to assign this behaviour is
> undesirable and does not solve the purpose of replicas.
> [~huaxiang] and [~enis].
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