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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Multiple data center performance
Date Wed, 12 Jun 2013 13:54:56 GMT
It is the normal behavior, but that's true of any update, not only of
counters.

The consistency level does *not* influence which replica are written to.
Cassandra always write to all replicas. The consistency level only decides
how replica acknowledgement are waited for.

--
Sylvain


On Wed, Jun 12, 2013 at 4:56 AM, Alain RODRIGUEZ <arodrime@gmail.com> wrote:

> "counter will replicate to all replicas during write regardless the
> consistency level"
>
> I that the normal behavior or a bug ?
>
>
> 2013/6/11 Daning Wang <daning@netseer.com>
>
>> It is counter caused the problem. counter will replicate to all replicas
>> during write regardless the consistency level.
>>
>> In our case. we don't need to sync the counter across the center. so
>> moving counter to new keyspace and all the replica in one
>> center solved problem.
>>
>> There is option replicate_on_write on table. If you turn that off for
>> counter might have better performance. but you are on high risk to lose
>> data and create inconsistency. I did not try this option.
>>
>> Daning
>>
>>
>> On Sat, Jun 8, 2013 at 6:53 AM, srmore <comomore@gmail.com> wrote:
>>
>>> I am seeing the similar behavior, in my case I have 2 nodes in each
>>> datacenter and one node always has high latency (equal to the latency
>>> between the two datacenters). When one of the datacenters is shutdown the
>>> latency drops.
>>>
>>> I am curious to know whether anyone else has these issues and if yes how
>>> did to get around it.
>>>
>>> Thanks !
>>>
>>>
>>> On Fri, Jun 7, 2013 at 11:49 PM, Daning Wang <daning@netseer.com> wrote:
>>>
>>>> We have deployed multi-center but got performance issue. When the nodes
>>>> on other center are up, the read response time from clients is 4 or 5 times
>>>> higher. when we take those nodes down, the response time becomes
>>>> normal(compare to the time before we changed to multi-center).
>>>>
>>>> We have high volume on the cluster, the consistency level is one for
>>>> read. so my understanding is most of traffic between data center should be
>>>> read repair. but seems that could not create much delay.
>>>>
>>>> What could cause the problem? how to debug this?
>>>>
>>>> Here is the keyspace,
>>>>
>>>> [default@dsat] describe dsat;
>>>> Keyspace: dsat:
>>>>   Replication Strategy:
>>>> org.apache.cassandra.locator.NetworkTopologyStrategy
>>>>   Durable Writes: true
>>>>     Options: [dc2:1, dc1:3]
>>>>   Column Families:
>>>>     ColumnFamily: categorization_cache
>>>>
>>>>
>>>> Ring
>>>>
>>>> Datacenter: dc1
>>>> ===============
>>>> Status=Up/Down
>>>> |/ State=Normal/Leaving/Joining/Moving
>>>> --  Address           Load       Tokens  Owns (effective)  Host ID
>>>>                           Rack
>>>> UN  xx.xx.xx..111       59.2 GB    256     37.5%
>>>> 4d6ed8d6-870d-4963-8844-08268607757e  rac1
>>>> DN  xx.xx.xx..121       99.63 GB   256     37.5%
>>>> 9d0d56ce-baf6-4440-a233-ad6f1d564602  rac1
>>>> UN  xx.xx.xx..120       66.32 GB   256     37.5%
>>>> 0fd912fb-3187-462b-8c8a-7d223751b649  rac1
>>>> UN  xx.xx.xx..118       63.61 GB   256     37.5%
>>>> 3c6e6862-ab14-4a8c-9593-49631645349d  rac1
>>>> UN  xx.xx.xx..117       68.16 GB   256     37.5%
>>>> ee6cdf23-d5e4-4998-a2db-f6c0ce41035a  rac1
>>>> UN  xx.xx.xx..116       32.41 GB   256     37.5%
>>>> f783eeef-1c51-4f91-ab7c-a60669816770  rac1
>>>> UN  xx.xx.xx..115       64.24 GB   256     37.5%
>>>> e75105fb-b330-4f40-aa4f-8e6e11838e37  rac1
>>>> UN  xx.xx.xx..112       61.32 GB   256     37.5%
>>>> 2547ee54-88dd-4994-a1ad-d9ba367ed11f  rac1
>>>> Datacenter: dc2
>>>> ===============
>>>> Status=Up/Down
>>>> |/ State=Normal/Leaving/Joining/Moving
>>>> --  Address           Load       Tokens  Owns (effective)  Host ID
>>>>                           Rack
>>>> DN  xx.xx.xx.199    58.39 GB   256     50.0%
>>>> 6954754a-e9df-4b3c-aca7-146b938515d8  rac1
>>>> DN  xx.xx.xx..61      33.79 GB   256     50.0%
>>>> 91b8d510-966a-4f2d-a666-d7edbe986a1c  rac1
>>>>
>>>>
>>>> Thank you in advance,
>>>>
>>>> Daning
>>>>
>>>>
>>>
>>
>

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