We are using JanusGraph 0.2.0 with Cassandra 3.11.1 and testing its support for geo diversity. Currently we have 2 Datacenters with 1 nodes in each and replication factor is 1 for both the datacenter.
janusgraph-cassandra.properties
storage.backend=cql
storage.cql.read-consistency-level=LOCAL_QUORUM
storage.cql.write-consistency-level=LOCAL_QUORUM
storage.cql.local-datacenter=dc2
storage.cql.only-use-local-consistency-for-system-operations=true
storage.cql.replication-strategy-options=dc1,1,dc2,1
storage.cql.replication-strategy-class = NetworkTopologyStrategy
When we have Cassandra running in both the nodes of datacenter, we are able to connect and create JanusGraph keyspace. However, when one datacenter goes down, and if we try to open a connection, we observe following exception:
com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.249.55.111:9042 (com.datastax.driver.core.exceptions.UnavailableException: Not enough replicas available for query at consistency QUORUM (2 required but only 1 alive)))
at com.datastax.driver.core.RequestHandler.reportNoMoreHosts(RequestHandler.java:211)
We have configured Local_Quorum, but still why is it using Quorum for establishing connection.
Update: nodetool status output
Datacenter: dc1
===============
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
-- Address Load Tokens Owns (effective) Host ID Rack
DN 10.249.55.108 283.54 KiB 256 100.0% 619242db-f0bd-4492-aeb6-2bb0ebfe4733 rack1
Datacenter: dc2
===============
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
-- Address Load Tokens Owns (effective) Host ID Rack
UN 10.249.55.111 294.75 KiB 256 100.0% 6ebe897e-94e3-44e5-99dc-055beb633e74 rack1
