[jira] Updated: (CASSANDRA-1569) New variant of NetworkTopologyStrategy to eliminate hotspots

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-1569?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis updated CASSANDRA-1569:
--------------------------------------

    Attachment: 1569.txt

> New variant of NetworkTopologyStrategy to eliminate hotspots
> ------------------------------------------------------------
>
>                 Key: CASSANDRA-1569
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1569
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 0.7 beta 1
>            Reporter: Stu Hood
>            Assignee: Stu Hood
>             Fix For: 0.7.0
>
>         Attachments: 1569.txt
>
>
> NetworkTopologyStrategy assigns replicas to the first endpoints encountered in the required DCs during a ring-order walk. This will lead to hotspots if you don't have an equal number of nodes in each DC, and if you don't alternate them in the ring.
> An alternate algorithm that prevents hotspots is to choose replicas using fractions. If the first replica is on the 4th node of 10 for a particular DC, its fractional position is 0.4: remaining replicas in other DCs will be placed on the node at that fractional position.

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