the steps are:
- ALTER KEYSPACE to change your replication strategy
- "nodetool repair -pr <yourkeyspace>" on ALL nodes or full repair
"nodetool repair <yourkeyspace>" on enough replica to distribute and
rebalance your data to replicas
- nodetool cleanup on every node to remove superfluous data

Please note that you'd better not query the cluster for reads as you will
ask data to replicas that doesn't have it yet until your repair is finished.


2017-09-14 4:04 GMT+07:00 Dominik Petrovic <[EMAIL PROTECTED]lid

> Dear community,
> I'd like to receive additional info on how to modify a keyspace
> replication strategy.
> My Cassandra cluster is on AWS, Cassandra 2.1.15 using vnodes, the
> cluster's snitch is configured to Ec2Snitch, but the keyspace the
> developers created has replication class SimpleStrategy = 3.
> During an outage last week we realized the discrepancy between the
> configuration and we would now fix the issue using NetworkTopologyStrategy.
> What are the suggested steps to perform?
> For Cassandra 2.1 I found only this doc: http://docs.datastax.com/
> en/cassandra/2.1/cassandra/operations/opsChangeKSStrategy.html
> that does not mention anything about repairing the cluster
> For Cassandra 3 I found this other doc: https://docs.datastax.
> com/en/cassandra/3.0/cassandra/operations/opsChangeKSStrategy.html
> That involves also the cluster repair operation.
> On a test cluster I tried the steps for Cassandra 2.1 but the token
> distribution in the ring didn't change so I'm assuming that wasn't the
> right think to do.
> I also perform a nodetool repair -pr but nothing changed as well.
> Some advice?
> --
> Dominik Petrovic

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