The token distribution isn't going to change - the way Cassandra maps replicas will change.
How many data centers/regions will you have when you're done? What's your RF now? You definitely need to run repair before you ALTER, but you've got a bit of a race here between the repairs and the ALTER, which you MAY be able to work around if we know more about your cluster. How many nodes How many regions How many replicas per region when you're done? -- Jeff Jirsa > On Sep 13, 2017, at 2:04 PM, Dominik Petrovic > <dominik.petro...@mail.ru.INVALID> wrote: > > 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
