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From Kunal <>
Subject Re: Unpair cassandra datacenters
Date Mon, 22 Apr 2019 23:00:25 GMT
HI Marc,

Appreciate your prompt response.

Yes we are starting datacenter B from scratch. We tried using cluster name
change on side B and it works but our requirement says we can not change
cluster name because during our product's major or patch release, the
scripts expect cluster name to be the same.
On datacenter B , we are changing the seeds nodes. On datacenter A , we are
changing the seeds nodes in cassandra.yml but that will be picked up during
cassandra restart only but we can not have downtime for datacenter A. It
has to be up all the time.

Kunal Vaid

On Mon, Apr 22, 2019 at 3:49 PM Marc Selwan <>

> Hi Kunal,
> Did you edit the cassandra.yaml file in each data center to remove the
> seed nodes? On which ever data center is starting from scratch (I think
> it's B in your case), you may want to also change the cluster name.
> Best,
> *Marc Selwan | *DataStax *| *PM, Server Team *|* *(925) 413-7079* *|*
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> On Mon, Apr 22, 2019 at 3:38 PM Kunal <> wrote:
>> Hi Friends,
>> I need small help in unpairing two datacenters.
>> We have 2 datacenters (say A and B ) with 3 nodes in each datacenter. We
>> want to remove one whole data center (B) (3 nodes) from the other one (B).
>> basically, want to unpair both datacenter and want to use them both
>> individually.
>> We are trying this using nodetool decommission and it is removing the 3
>> nodes from B datacenter. But when we are trying to bring up datacenter B to
>> use it separately from Datacenter A, it is joining back to datacenter A. We
>> noticed in debug.log, nodes from datacenter A keeps looking for nodes in
>> datacenter B and getting connection refused error when the nodes of
>> datacenter B are down, but as soon as nodes comes back, they are joining to
>> the cluster.
>> We don't want nodes from datacenter B to join datacenter A once they are
>> decommissioned.
>> Can you please let me know if i am missing anything.
>> Thanks in advance.
>> Regards,
>> Kunal Vaid


Kunal Vaid

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