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Re: system_auth keyspace replication factor


Any chance you’re logging in with the Cassandra user? It uses quorum reads. 


On Fri, Nov 23, 2018 at 11:38 AM Vitali Dyachuk <vdjatsuk@xxxxxxxxx> wrote:
Hi,
We have recently met a problem when we added 60 nodes in 1 region to the cluster
and set an RF=60 for the system_auth ks, following this documentation https://docs.datastax.com/en/cql/3.3/cql/cql_using/useUpdateKeyspaceRF.html
However we've started to see increased login latencies in the cluster 5x bigger than before changing RF of system_auth ks.
We have casandra runner written is csharp, running against the cluster, when analyzing the logs we notices that   Rebuilding token map  is taking most of the time ~20s.
When we changed RF to 3 the issue has resolved.
We are using C* 3.0.17 , 4 DC, system_auth RF=3, "CassandraCSharpDriver" version="3.2.1"   
I've found somehow related to my problem ticket https://datastax-oss.atlassian.net/browse/CSHARP-436 but it says in the related tickets, that the issue with the token map rebuild time has been fixed in the previous versions of the driver.
So my question is what is the best recommendation of the setting system_auth ks RF?

Regards,
Vitali Djatsuk.


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