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From Elliot Finley <efinley.li...@gmail.com>
Subject Re: mixed nodes, some SSD some HD
Date Wed, 05 Mar 2014 22:48:50 GMT
How does giving the SSD node a higher number of tokens help anything if
it's a 3 node cluster with 3 replicas?



On Wed, Mar 5, 2014 at 3:41 PM, Tyler Hobbs <tyler@datastax.com> wrote:

> The dynamic snitch wraps whatever snitch you configure (SimpleSnitch,
> PropertyFileSnitch, etc).
>
> The dynamic snitch *will* favor faster replicas, but it might still
> under-utilize the SSD nodes.  Chris's suggestion to give the SSD nodes a
> higher number of tokens will result in them being replicas for a larger
> portion of the data, so you may still want to do that.
>
>
> On Wed, Mar 5, 2014 at 4:29 PM, Russell Bradberry <rbradberry@gmail.com>wrote:
>
>> Are you using the dynamic snitch? Because the SimpleSnitch is the default.
>>
>>
>>
>> On March 5, 2014 at 5:27:03 PM, Elliot Finley (efinley.lists@gmail.com)
>> wrote:
>>
>> Keep in mind, for this 3 node cluster, N = 3.
>>
>> I did a bit more digging and I found this (for future searches on this
>> topic):
>>
>> http://www.datastax.com/documentation/cassandra/2.0/cassandra/architecture/architectureSnitchDynamic_c.html
>>
>> http://www.datastax.com/dev/blog/dynamic-snitching-in-cassandra-past-present-and-future
>>
>> So, according to this, if I'm reading it right, the SSD node WILL take
>> the majority of reads.
>>
>> Any comments welcome.
>>
>>
>>
>> On Wed, Mar 5, 2014 at 10:04 AM, Chris Burroughs <
>> chris.burroughs@gmail.com> wrote:
>>
>>> No.  If you have a heterogeneous clusters you should consider adjusting
>>> the number of vnodes per physical node.
>>>
>>>
>>> On 03/04/2014 10:47 PM, Elliot Finley wrote:
>>>
>>>> Using Cassandra 2.0.x
>>>>
>>>> If I have a 3 node cluster and 2 of the nodes use spinning drives and 1
>>>> of
>>>> them uses SSD,  will the majority of the reads be routed to the SSD node
>>>> automatically because it has faster responses?
>>>>
>>>> TIA,
>>>> Elliot
>>>>
>>>>
>>>
>>
>
>
> --
> Tyler Hobbs
> DataStax <http://datastax.com/>
>

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