Puzzeling Spark Warning (DSE 4.8.4)

Question

I just stumbled upon a strange warning on a Spark remote (DSE 4.8.4) that I have no clue where it came from. He seems to be collecting DC1 data center somewhere. The fact is that I do not have a datacenter called DC1. I have three data centers, but no one is flagged this way.

WARN 2016-01-21 05:26:54 com.datastax.driver.core.ReplicationStrategy $ NetworkTopologyStrategy: error calculating token map for DC1 data center: could not reach replication coefficient 1 (only 0 replicas found), check the key replication settings. Please note that this may affect driver performance.

Answer 1

This is a message issued by the java driver that indicates that one of your keys contains "DC1" in its replication rate. This can lead to slow initialization in the java driver if you have many nodes or use vnodes, because it is connected with the worst situation, to try to find matching replicas (this is fixed, but still written in java 2.0.11 / 2.1.8, JAVA-859 ).

To find out what this describe schemakeyspace is, run a cqlsh session that should print all of your schema definitions. Look for definitions create keyspaceand observe them replication_strategy, that is:

CREATE KEYSPACE myks WITH replication = {'class': 'NetworkTopologyStrategy', 'DC1': '3'}  AND durable_writes = true;

java- , (JAVA-989).