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From kurt Greaves <k...@instaclustr.com>
Subject Re: How to change Replication Strategy and RF
Date Fri, 30 Dec 2016 00:28:26 GMT
‚ÄčIf you're already using the cluster in production and require no downtime
you should perform a datacenter migration first to change the RF to 3.
Rough process would be as follows:

   1. Change keyspace to NetworkTopologyStrategy with RF=1. You shouldn't
   increase RF here as you will receive read failures as not all nodes have
   the data they own. You would have to wait for a repair to complete to stop
   any read failures.
   2. Configure your clients to use a LOCAL_* consistency and
   DCAwareRoundRobinPolicy for load balancing (with the current DC configured)
   3. Add a new datacenter, configure it's replication to be 3.
   4. Rebuild the new datacenter by running nodetool rebuild <old-dc> on
   each node in the new DC.
   5. Migrate your clients to use the new datacenter, by switching the
   contact points to nodes in the new DC and the load balancing policy DC to
   the new DC
   6. At this point you could increase the replication factor on the old DC
   to 3, and then run a repair. Once the repair successfully completes you
   should have 2 DCs that you can use. If you need the DCs in separate
   locations you could change this step to adding another DC in the desired
   other location and running rebuilds as per steps 2-4.

- Kurt

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