[jira] [Updated] (HELIX-141) Autorebalance does not work reliably and fails when replica>1

["Kanak Biscuitwala (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HELIX-141?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kanak Biscuitwala updated HELIX-141:
------------------------------------

    Fix Version/s: 0.6.2-incubating

> Autorebalance does not work reliably and fails when replica>1
> -------------------------------------------------------------
>
>                 Key: HELIX-141
>                 URL: https://issues.apache.org/jira/browse/HELIX-141
>             Project: Apache Helix
>          Issue Type: Bug
>            Reporter: kishore gopalakrishna
>            Assignee: Kanak Biscuitwala
>             Fix For: 0.6.2-incubating
>
>         Attachments: 0001-HELIX-141-Auto-rebalancer-that-works-for-arbitrary-p.patch
>
>
> Autorebalance has a bug in calculating the assignment of partitions to nodes. It does not consider the fact that  a partition can have replicas. This was not tested because we generally use 1 replica ( consumer grouping). 
> As we are doing this, we might want to fix/add the following features
> #1. Allow user to set a minimum number of nodes to be up before computing the assignment. This minimizes the number of re-assignments when nodes start up.
> #2. Have the concept of preferred node for a partition,replica. Which means when ever a partition,replica is orphaned try to first place it on its preferred location. Preferred location can be something like (p+r)%N. This will require us to use the total number of nodes to compute the preferred location. 



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