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From vd <vineetdan...@gmail.com>
Subject Re: what is DCQUORUM
Date Wed, 12 May 2010 14:28:26 GMT
Thanks Eben


On Wed, May 12, 2010 at 7:33 PM, Eben Hewitt <eben.hewitt@gmail.com> wrote:

> QUORUM is a high consistency level. It refers to the number of nodes that
> have to acknowledge read or write operations in order to be assured that
> Cassandra is in a consistent state. It uses <ReplicationFactor> / 2 + 1.
>
> DCQUORUM means "Data Center Quorum", and balances consistency with
> performance. It puts multiple replicas in each Data Center so operations can
> prefer replicas in the same DC for lower latency.
>
> See https://issues.apache.org/jira/browse/CASSANDRA-492 for a little
> discussion.
>
> Also see
> http://svn.apache.org/repos/asf/cassandra/trunk/src/java/org/apache/cassandra/locator/DatacenterShardStrategy.java
>  and
>
> http://svn.apache.org/repos/asf/cassandra/trunk/src/java/org/apache/cassandra/service/DatacenterWriteResponseHandler.java
>
> Eben
>
>
>
> On Wed, May 12, 2010 at 6:15 AM, vd <vineetdaniel@gmail.com> wrote:
>
>> Hi
>>
>> I have read about QUORUM but lately came across DCQUORUM. What is it  and
>> whats the difference between the two ?
>>
>>
>
>
> --
> "In science there are no 'depths'; there is surface everywhere."
> --Rudolph Carnap
>

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