Hi Marcel, The RF for that keyspace is currently hardcoded, see CASSANDRA-11098 <https://issues.apache.org/jira/browse/CASSANDRA-11098>. I am not sure why your RF switched from 1 to 3 after you restarted a cluster, I tried the same and it remained at 1 for me.
The tables in that keyspace are used to store history about the repair operations, having it as RF=3 shouldn't affect the performance of the repair. See CASSANDRA-5839 <https://issues.apache.org/jira/browse/CASSANDRA-5839> for when / why it was introduced. Changing the replication from 3 to 1 for system_distributed is not a good idea for the same reasons why changing the replication of *any* keyspace to 1 is not a good idea. You lose the ability to query that data if a single node goes down. Hope this helps, Chris On Wed, Jan 8, 2020 at 1:23 AM Marcel Jakobi <m...@ordix.de> wrote: > Hi, > > > > the default definition of the keyspace system_distributed is: > > CREATE KEYSPACE system_distributed WITH replication = {'class': > 'SimpleStrategy', 'replication_factor': '3'} AND durable_writes = true; > > > > > > If I understand correctly, every repair information will be replicated on > three servers in the cluster. I have changed the RF to ‚1‘. Once i stop the > entire cluster, the replication factor changes again to 3. It seems > Cassandra wants it to be 3. > > > > Doesn`t that reduce performance on repair operation? > > Why is the RF changed again after restart the cluster? > > Are there reasons why you shouldn`t change the replication factor to 1? > > > > Thanks, > > Marcel >
