[infinispan-issues] [JBoss JIRA] (ISPN-3244) TopologyAwareSyncConsistentHashFactory should limit the number of segments per node

[Pedro Ruivo (JIRA)]

     [ https://issues.jboss.org/browse/ISPN-3244?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Pedro Ruivo updated ISPN-3244:
------------------------------
    Fix Version/s: 7.1.0.Beta1
                       (was: 7.1.0.Alpha1)


> TopologyAwareSyncConsistentHashFactory should limit the number of segments per node
> -----------------------------------------------------------------------------------
>
>                 Key: ISPN-3244
>                 URL: https://issues.jboss.org/browse/ISPN-3244
>             Project: Infinispan
>          Issue Type: Bug
>          Components: State Transfer
>    Affects Versions: 5.2.6.Final, 5.3.0.CR2
>            Reporter: Dan Berindei
>             Fix For: 7.1.0.Beta1
>
>
> Let's say we have a cluster with 5 nodes: A(r1), B(r2), C(r2), D(r3), E(r3)
> TopologyAwareConsistentSyncHashFactory will spread the segments equally on each rack, meaning A will own 2x segments compared to the other nodes.
> TopologyAwareConsistentHashFactory limits the maximum number per node, so that A owns just as many segments as the other nodes. With a slight limitation: the number of racks must be greater than numOwners, otherwise each rack must hold (at least) one copy of all the data.
> TopologyAwareConsistentSyncHashFactory is a little random, so we can't distribute the data perfectly, but we can limit the number of segments on each node to something like 1.5x the average number of segments.



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