[jira] [Commented] (HELIX-540) Full-auto rebalancer not able to map all partitions

["Zhen Zhang (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HELIX-540?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14203637#comment-14203637 ] 

Zhen Zhang commented on HELIX-540:
----------------------------------

This is caused by HELIX-541(https://issues.apache.org/jira/browse/HELIX-541)

> Full-auto rebalancer not able to map all partitions 
> ----------------------------------------------------
>
>                 Key: HELIX-540
>                 URL: https://issues.apache.org/jira/browse/HELIX-540
>             Project: Apache Helix
>          Issue Type: Bug
>            Reporter: Zhen Zhang
>
> We discover a bug where full-auto rebalancer not be able to mapping all partitions even when capacity is enough.
> Assuming we have 2 partition and 2 node, state model is LeaderStandby and replica is 1. For some reason, the current state mapping becomes:
> {noformat}
> partition_0:
>   node_0: LEADER
>   node_1: STANDBY
> {noformat}
> The extra STANDBY mapping prevents the full-auto rebalancer (AutoRebalanceStrategy#computePartitionAssignment) to assign LEADER to partition_1, so partition_1 will remain unmapped even though node capacity is enough.
> For workaround, we can disable the partition in STANDBY state on the node, thus "frees" the quota and the unmapped partition will get assigned LEADER. We can then re-enable the partition on the node.



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