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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: node selection for replication factor 3
Date Mon, 03 Oct 2011 22:19:29 GMT
On Mon, Oct 3, 2011 at 6:16 PM, Jonathan Ellis <jbellis@gmail.com> wrote:

> Depends on the replication strategy used.
>
> http://www.datastax.com/docs/0.8/cluster_architecture/replication
>
> On Mon, Oct 3, 2011 at 4:06 PM, Ramesh Natarajan <ramesh25@gmail.com>
> wrote:
> >
> > I have 6 nodes in a cluster running RandonPartitioner with SimpleStrategy
> > and replication factor 3.  Lets say we insert a column with
> > a QUORUM consistency.
> > Based on the md5 hash it decides to go to node 10.19.104.11. How does
> > cassandra pick the other 2 nodes? Is it sequential ( .12 and .13 ) or any
> > random node?
> > thanks
> > Ramesh
> >
> >
> > root@CAP4-CNode4 apache-cassandra-0.8.6]# ./bin/nodetool -h 127.0.0.1
> ring
> > Address         DC          Rack        Status State   Load
>  Owns
> >    Token
> >
> >    141784319550391026443072753096570088105
> > 10.19.104.11    datacenter1 rack1       Up     Normal  19.92 GB
> >  16.67%  0
> > 10.19.104.12    datacenter1 rack1       Up     Normal  19.3 GB
> > 16.67%  28356863910078205288614550619314017621
> > 10.19.104.13    datacenter1 rack1       Up     Normal  18.57 GB
> >  16.67%  56713727820156410577229101238628035242
> > 10.19.104.14    datacenter1 rack1       Up     Normal  19.34 GB
> >  16.67%  85070591730234615865843651857942052863
> > 10.19.105.11    datacenter1 rack1       Up     Normal  19.88 GB
> >  16.67%  113427455640312821154458202477256070484
> > 10.19.105.12    datacenter1 rack1       Up     Normal  20 GB
> > 16.67%  141784319550391026443072753096570088105
> > [root@CAP4-CNode4 apache-cassandra-0.8.6]#
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of DataStax, the source for professional Cassandra support
> http://www.datastax.com
>

Eric did a great walk through code dive on exactly how this works for
NetworkTopologyStrategy
http://files.meetup.com/1794037/NTS_presentation.pdf

Edward

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