Thanks Tyler,
I see that cassandra.yaml has "endpoint_snitch:
com.datastax.bdp.snitch.DseSimpleSnitch". Will this pick up the
configuration from the cassandra-topology.properties file as does the
PropertyFileSnitch ? Or is there some other way of telling it which nodes
are in withc DC?
Cheers,
Alex
On Wed, Mar 14, 2012 at 9:09 PM, Tyler Hobbs <ty...@datastax.com> wrote:
> Yes, you can do this.
>
> You will want to have three DCs: DC1 with [1, 2, 3], DC2 with [4, 5, 6],
> and DC3 with [7, 8, 9]. For your normal data keyspace, the replication
> strategy should be NTS, and the strategy_options should have some replicas
> in each of the three DCs. For example: {DC1: 3, DC2: 3, DC3: 3} if you
> need that level of replication in each one (although you probably only want
> an RF of 1 for DC3).
>
> Your clients that are performing writes should only open connections
> against the nodes in DC1, and you should write at CL.ONE or
> CL.LOCAL_QUORUM. Likewise for reads, your clients should only connect to
> nodes in DC2, and you should read at CL.ONE or CL.LOCAL_QUORUM.
>
> The nodes in DC3 should run as analytics nodes. I believe the default CL
> for m/r jobs is ONE, which would work.
>
> As far as tokens go, interleaving all three DCs and evenly spacing the
> tokens will work. For example, the ordering of your nodes might be [1, 4,
> 7, 2, 5, 8, 3, 6, 9].
>
>
> On Wed, Mar 14, 2012 at 12:05 PM, Alexandru Sicoe <adsi...@gmail.com>wrote:
>
>> Hi everyone,
>> I want to test out the Datastax Enterprise software to have a mixed
>> workload setup with an analytics and a real time part.
>>
>> However I am not sure how to configure it to achieve what I want: I will
>> have 3 real machines on one side of a gateway (1,2,3) and 6 VMs on
>> another(4,5,6).
>> 1,2,3 will each have a normal Cassandra node that just takes data
>> directly from my data sources. I want them to replicate the data to the
>> other 6 VMs. Now, out of those 6 VMs 4,5,6 will run normal Cassandra nodes
>> and 7,8,9 will run Analytics nodes. So I only want to write to the 1,2,3
>> and I only want to serve user reads from 4,5,6 and do analytics on 7,8,9.
>> Can I achieve this by configuring 1,2,3,4,5,6 as normal nodes and the rest
>> as analytics nodes? If I alternate the tokens as it's explained in
>> http://www.datastax.com/docs/1.0/datastax_enterprise/init_dse_cluster#init-dseis
>> it analoguous to achieving something like 3 DCs each getting their own
>> replica?
>>
>> Thanks,
>> Alex
>>
>>
>
>
> --
> Tyler Hobbs
> DataStax <http://datastax.com/>
>
>
