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https://issues.apache.org/jira/browse/KAFKA-1752?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dmitry Pekar updated KAFKA-1752:
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    Description:     (was: Current implementation produces fair replica 
distribution between specified list of brokers. Unfortunately, it doesn't take
into account current replica assignment. 

So if we have, for instance, 3 brokers id=[0..2] and are going to add fourth 
broker id=3, 
generate will create an assignment config which will redistribute replicas 
fairly accross brokers [0..3] 
in the same way as those partitions were created from scratch.

It will not take into consideration current replica assignment and accordingly 
will not try to minimize number 
of replica moves between brokers.

As proposed by [~charmalloc] this should be improved. New output of improved 
--generate algorithm should suite following requirements:
- fairness of replica distribution - every broker will have R or R+1 replicas 
assigned;
- minimum of reassignments - number of replica moves between brokers will be 
minimal;

Example.
Consider following replica distribution per brokers [0..3] (we just added 
brokers 2 and 3):
broker   - 0, 1, 2, 3 
replicas - 7, 6, 0, 0

The new algorithm will produce following assignment:
broker   -  0,  1,  2,  3 
replicas -  4,  3,  3,  3
moves    - -3, -3, +3, +3

It will be fair and number of moves will be 6, which is minimal for specified 
initial distribution.

The scope of this issue is:
- design an algorithm matching the above requirements;
- implement this algorithm and unit tests;
- test it manually using different initial assignments;)
        Summary: add --replace-broker option  (was: change behavior of 
--generate to produce assignment config with fair replica distribution and 
minimal number of reassignments)

> add --replace-broker option
> ---------------------------
>
>                 Key: KAFKA-1752
>                 URL: https://issues.apache.org/jira/browse/KAFKA-1752
>             Project: Kafka
>          Issue Type: Sub-task
>          Components: tools
>            Reporter: Dmitry Pekar
>            Assignee: Dmitry Pekar
>             Fix For: 0.8.3
>
>




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