Sorry for that last message, I was confused because I thought I needed to
use the DseSimpleSnitch but of course I can use the PropertyFileSnitch and
that allows me to get the configuration with 3 data centers explained.
Cheers,
Alex
On Thu, Mar 15, 2012 at 10:56 AM, Alexandru Sicoe <adsi...@gmail.com> wrote:
> 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/>
>>
>>
>
