> As far as I know there isn't any way to use the rack name in the
> strategy_options for a keyspace. You
> might want to look at the code to dig into that, perhaps.
Aha, I was wondering if I could do that as well ( specify rack options ) :)
Thanks for the pointer, I will dig into the code.
-Thanks,
Prasenjit
On Thu, Jul 12, 2012 at 5:33 AM, Richard Lowe <richard.l...@arkivum.com> wrote:
> If you then specify the parameters for the keyspace to use these, you can
> control exactly which set of nodes replicas end up on.
>
> For example, in cassandra-cli:
>
> create keyspace ks1 with placement_strategy =
> 'org.apache.cassandra.locator.NetworkTopologyStrategy' and strategy_options =
> { DC1_realtime: 2, DC1_analytics: 1, DC2_realtime: 1 };
>
> As far as I know there isn't any way to use the rack name in the
> strategy_options for a keyspace. You might want to look at the code to dig
> into that, perhaps.
>
> Whichever snitch you use, the nodes are sorted in order of proximity to the
> client node. How this is determined depends on the snitch that's used but
> most (the ones that ship with Cassandra) will use the default ordering of
> same-node < same-rack < same-datacenter < different-datacenter. Each snitch
> has methods to tell Cassandra which rack and DC a node is in, so it always
> knows which node is closest. Used with the Bloom filters this can tell us
> where the nearest replica is.
>
>
>
> -----Original Message-----
> From: prasenjit mukherjee [mailto:prasen....@gmail.com]
> Sent: 11 July 2012 06:33
> To: user
> Subject: How to come up with a predefined topology
>
> Quoting from
> http://www.datastax.com/docs/0.8/cluster_architecture/replication#networktopologystrategy
> :
>
> "Asymmetrical replication groupings are also possible depending on your use
> case. For example, you may want to have three replicas per data center to
> serve real-time application requests, and then have a single replica in a
> separate data center designated to running analytics."
>
> Have 2 questions :
> 1. Any example how to configure a topology with 3 replicas in one DC ( with 2
> in 1 rack + 1 in another rack ) and one replica in another DC ?
> The default networktopologystrategy with rackinferringsnitch will only give
> me equal distribution ( 2+2 )
>
> 2. I am assuming the reads can go to any of the replicas. Is there a client
> which will send query to a node ( in cassandra ring ) which is closest to the
> client ?
>
> -Thanks,
> Prasenjit
>
>
