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From Chris Burroughs <chris.burrou...@gmail.com>
Subject Re: Multi-dc restart impact
Date Thu, 10 Oct 2013 00:41:15 GMT
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
  * perf in other DC: 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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