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From aaron morton <aa...@thelastpickle.com>
Subject Re: Replication factor
Date Thu, 24 May 2012 10:00:12 GMT
Your experience is when using CL ONE the Dynamic Snitch is moving local reads off to other
nodes and this is causing spikes in read latency ? 

Did you notice what was happening on the node for the DS to think it was so slow ? Was compaction
or repair going on ? 
 
Have you played with the badness threshold https://github.com/apache/cassandra/blob/trunk/conf/cassandra.yaml#L472
? 

Cheers


-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 24/05/2012, at 5:28 PM, Viktor Jevdokimov wrote:

> Depends on use case. For ours we have another experience and statistics, when turning
dynamic snitch off makes overall latency and spikes much, much lower.
>  
>  
> 
> 
> Best regards / Pagarbiai
> Viktor Jevdokimov
> Senior Developer
> 
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> 
> From: Brandon Williams [mailto:driftx@gmail.com] 
> Sent: Thursday, May 24, 2012 02:35
> To: user@cassandra.apache.org
> Subject: Re: Replication factor
>  
> On Wed, May 23, 2012 at 5:51 AM, Viktor Jevdokimov <Viktor.Jevdokimov@adform.com>
wrote:
> > When RF == number of nodes, and you read at CL ONE you will always be reading locally.
> “always be reading locally” – only if Dynamic Snitch is “off”. With dynamic
snitch “on” request may be redirected to other node, which may introduce latency spikes.
>  
> Actually it's preventing spikes, since if it won't read locally that means the local
replica is in worse shape than the rest (compacting, repairing, etc.)
>  
> -Brandon 


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