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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: quorum calculation seems to depend on previous selected nodes
Date Mon, 17 Jan 2011 16:08:39 GMT
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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