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Posted to jira@kafka.apache.org by "Jason Gustafson (JIRA)" <ji...@apache.org> on 2018/04/16 17:48:00 UTC

[jira] [Updated] (KAFKA-6794) Support for incremental replica reassignment

     [ https://issues.apache.org/jira/browse/KAFKA-6794?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jason Gustafson updated KAFKA-6794:
-----------------------------------
    Description: 
Say you have a replication factor of 4 and you trigger a reassignment which moves all replicas to new brokers. Now 8 replicas are fetching at the same time which means you need to account for 8 times the current producer load plus the catch-up replication. To make matters worse, the replicas won't all become in-sync at the same time; in the worst case, you could have 7 replicas in-sync while one is still catching up. Currently, the old replicas won't be disabled until all new replicas are in-sync. This makes configuring the throttle tricky since ISR traffic is not subject to it.

Rather than trying to bring all 4 new replicas online at the same time, a friendlier approach would be to do it incrementally: bring one replica online, bring it in-sync, then remove one of the old replicas. Repeat until all replicas have been changed. This would reduce the impact of a reassignment and make configuring the throttle easier at the cost of a slower overall reassignment.

  was:
Say you have a replication factor of 4 and you trigger a reassignment which moves all replicas to new brokers. Now 8 replicas are fetching at the same time which means you need to account for 8 times the current load plus the catch-up replication. To make matters worse, the replicas won't all become in-sync at the same time; in the worst case, you could have 7 replicas in-sync while one is still catching up. Currently, the old replicas won't be disabled until all new replicas are in-sync. This makes configuring the throttle tricky since ISR traffic is not subject to it.

Rather than trying to bring all 4 new replicas online at the same time, a friendlier approach would be to do it incrementally: bring one replica online, bring it in-sync, then remove one of the old replicas. Repeat until all replicas have been changed. This would reduce the impact of a reassignment and make configuring the throttle easier at the cost of a slower overall reassignment.


> Support for incremental replica reassignment
> --------------------------------------------
>
>                 Key: KAFKA-6794
>                 URL: https://issues.apache.org/jira/browse/KAFKA-6794
>             Project: Kafka
>          Issue Type: Improvement
>            Reporter: Jason Gustafson
>            Priority: Major
>
> Say you have a replication factor of 4 and you trigger a reassignment which moves all replicas to new brokers. Now 8 replicas are fetching at the same time which means you need to account for 8 times the current producer load plus the catch-up replication. To make matters worse, the replicas won't all become in-sync at the same time; in the worst case, you could have 7 replicas in-sync while one is still catching up. Currently, the old replicas won't be disabled until all new replicas are in-sync. This makes configuring the throttle tricky since ISR traffic is not subject to it.
> Rather than trying to bring all 4 new replicas online at the same time, a friendlier approach would be to do it incrementally: bring one replica online, bring it in-sync, then remove one of the old replicas. Repeat until all replicas have been changed. This would reduce the impact of a reassignment and make configuring the throttle easier at the cost of a slower overall reassignment.



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