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From David Boxenhorn <da...@lookin2.com>
Subject Re: quorum calculation seems to depend on previous selected nodes
Date Mon, 17 Jan 2011 17:54:05 GMT
I think you should just tell everybody that if you want to use QUORUM you
need RF >= 3 for it to be meaningful.

No one would use QUORUM with RF < 3 except in error.

On Mon, Jan 17, 2011 at 6:08 PM, Jonathan Ellis <jbellis@gmail.com> wrote:

> On Mon, Jan 17, 2011 at 9:55 AM, Samuel Benz <samuel.benz@switch.ch>
> wrote:
> > We have a cluster with 4 nodes. ReplicationFactor is 2, ReplicaPlacment
> > is the RackAwareStrategy and the EndpointSnitch is the
> > PropertyFileEndpointSnitch (with two data center and two racks each).
> >
> > My understanding is, that with this parameter of the cluster, it should
> > be possible to update with consistency level quorum while one data
> > center (two nodes) are shutdown completely.
>
> No.  Quorum of 2 is 2.
>
> > Case1:
> > If 'TEST' was previous stored on Node1, Node2, Node3 -> The update will
> > succeed.
> >
> > Case2:
> > If 'TEST' was previous stored on Node2, Node3, Node4 -> The update will
> > not work.
>
> If you have RF=2 then it will be stored on 2 nodes, not 3.  I think
> this is the source of the confusion.
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of Riptano, the source for professional Cassandra support
> http://riptano.com
>

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