Hi Kunal, The simple solution for this case would be as follows,
1. Run *Full repair.* 2. Add firewall to block network on port 7000(,7001 if ssl enabled) between two datacenter nodes. 3. Check the status of cassandra cluster from both data centers, each DC must show down node status of another DC nodes after the firewall change. 4. Change replication factor for all keyspaces on each data center. 5. Start decommissioning nodes from each datacenter (Should be removenode in this case). 6. Update seeds list on each datacenter to local datacenter nodes and perform a rolling restart. Hope this helps, Try to test this scenario on non-prod system first. Thanks, Sandeep On Tue, Apr 23, 2019 at 11:00 AM Kunal <kunal.v...@gmail.com> wrote: > 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. > > > Regards, > Kunal Vaid > > > On Mon, Apr 22, 2019 at 3:49 PM Marc Selwan <marc.sel...@datastax.com> > wrote: > >> 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* *|* >> Twitter <https://twitter.com/MarcSelwan> >> >> * Quick links | *DataStax <http://www.datastax.com> *| *Training >> <http://www.academy.datastax.com> *| *Documentation >> <http://www.datastax.com/documentation/getting_started/doc/getting_started/gettingStartedIntro_r.html> >> *| *Downloads <http://www.datastax.com/download> >> >> >> >> On Mon, Apr 22, 2019 at 3:38 PM Kunal <kunal.v...@gmail.com> 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 >>> >> > > -- > > > > Regards, > Kunal Vaid >
