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From aaron morton <aa...@thelastpickle.com>
Subject Re: How to avoid inter-dc read requests
Date Tue, 23 Jul 2013 09:02:10 GMT
> All the read/write request are issued with CL local quorum, but still there're a lot of
inter-dc read request.
> 
How are you measuring this ?

Cheers

-----------------
Aaron Morton
Cassandra Consultant
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 22/07/2013, at 8:41 AM, sankalp kohli <kohlisankalp@gmail.com> wrote:

> Slice query does not trigger background read repair. 
> Implement Read Repair on Range Queries
> 
> 
> On Sun, Jul 21, 2013 at 1:40 PM, sankalp kohli <kohlisankalp@gmail.com> wrote:
> There can be multiple reasons for that
> 1) Background read repairs.
> 2) Your data is not consistent and leading to read repairs. 
> 3) For writes, irrespective of the consistency used, a single write request will goto
other DC
> 4) You might be running other nodetools commands like repair.
> read_repair_chanceĀ¶
> 
> (Default: 0.1 or 1) Specifies the probability with which read repairs should be invoked
on non-quorum reads. The value must be between 0 and 1. For tables created in versions of
Cassandra before 1.0, it defaults to 1. For tables created in versions of Cassandra 1.0 and
higher, it defaults to 0.1. However, for Cassandra 1.0, the default is 1.0 if you use CLI
or any Thrift client, such as Hector or pycassa, and is 0.1 if you use CQL.
> 
> 
> 
> On Sun, Jul 21, 2013 at 10:26 AM, Omar Shibli <omar@eyeviewdigital.com> wrote:
> One more thing, I'm doing a lot of key slice read requests, is that supposed to change
anything? 
> 
> 
> On Sun, Jul 21, 2013 at 8:21 PM, Omar Shibli <omar@eyeviewdigital.com> wrote:
> I'm seeing a lot of inter-dc read requests, although I've followed DataStax guidelines
for multi-dc deployment http://www.datastax.com/dev/blog/deploying-cassandra-across-multiple-data-centers
> 
> Here is my setup:
> 2 data centers within the same region (AWS)
> Targeting DC, RP 3, 6 nodes
> Analytic DC, RP 3, 11 nodes
> 
> All the read/write request are issued with CL local quorum, but still there're a lot
of inter-dc read request.
> Any suggestion, or am I missing something?
> 
> Thanks in advance,
> 
> 
> 


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