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From Chris Burroughs <chris.burrou...@gmail.com>
Subject Re: Multi-dc restart impact
Date Thu, 10 Oct 2013 16:50:38 GMT
Thanks, double checked; reads are CL.ONE.

On 10/10/2013 11:15 AM, J. Ryan Earl wrote:
> Are you doing QUORUM reads instead of LOCAL_QUORUM reads?
>
>
> On Wed, Oct 9, 2013 at 7:41 PM, Chris Burroughs
> <chris.burroughs@gmail.com>wrote:
>
>> I have not been able to do the test with the 2nd cluster, but have been
>> given a disturbing data point.  We had a disk slowly fail causing a
>> significant performance degradation that was only resolved when the "sick"
>> node was killed.
>>   * Perf in DC w/ sick disk: http://i.imgur.com/W1I5ymL.**png?1<http://i.imgur.com/W1I5ymL.png?1>
>>   * perf in other DC: http://i.imgur.com/gEMrLyF.**png?1<http://i.imgur.com/gEMrLyF.png?1>
>>
>> Not only was a single slow node able to cause an order of magnitude
>> performance hit in a dc, but the other dc faired *worse*.
>>
>>
>> On 09/18/2013 08:50 AM, Chris Burroughs wrote:
>>
>>> On 09/17/2013 04:44 PM, Robert Coli wrote:
>>>
>>>> On Thu, Sep 5, 2013 at 6:14 AM, Chris Burroughs
>>>> <chris.burroughs@gmail.com>**wrote:
>>>>
>>>>   We have a 2 DC cluster running cassandra 1.2.9.  They are in actual
>>>>> physically separate DCs on opposite coasts of the US, not just logical
>>>>> ones.  The primary use of this cluster is CL.ONE reads out of a single
>>>>> column family.  My expectation was that in such a scenario restarts
>>>>> would
>>>>> have minimal impact in the DC where the restart occurred, and no
>>>>> impact in
>>>>> the remote DC.
>>>>>
>>>>> We are seeing instead that restarts in one DC have a dramatic impact
on
>>>>> performance in the other (let's call them DCs "A" and "B").
>>>>>
>>>>>
>>>> Did you end up filing a JIRA on this, or some other outcome?
>>>>
>>>> =Rob
>>>>
>>>>
>>>
>>> No.  I am currently in the process of taking a 2nd cluster from being
>>> single to dual DC.  Once that is done I was going to repeat the test
>>> with each cluster and gather as much information as reasonable.
>>>
>>
>>
>


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