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From Tyler Hobbs <ty...@datastax.com>
Subject Re: mixed nodes, some SSD some HD
Date Wed, 05 Mar 2014 22:41:34 GMT
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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