Hey Tom, What's your replication strategy look like? When your new nodes join the ring, can you verify that they show up under a new DC and not as part of the old?
--Bryan On Thu, Sep 3, 2015 at 11:27 AM, Tom van den Berge < tom.vandenbe...@gmail.com> wrote: > I want to start using vnodes in my cluster. To do so, I've set up a new > data center with the same number of nodes as the existing one, as described > in > http://docs.datastax.com/en/cassandra/2.0/cassandra/configuration/configVnodesProduction_t.html. > The new DC is in the same physical location as the old one. > > The problem I'm running into is that as soon as the nodes in the new data > center are started, the application that is using the nodes in the old data > center is frequently getting error messages because queries don't return > the expected data. I'm pretty sure this is because somehow these queries > are routed to the new, empty data center. The application is not connecting > to the nodes in the new DC. > > I've tried two different things to prevent this: > > 1) Ensure that all queries use either LOCAL_ONE or LOCAL_QUORUM > consistency. Nevertheless, I'm still seeing failed queries. > 2) Start the new nodes with -Dcassandra.join_ring=false, to prevent them > from participating in the cluster. Although they don't show up in nodetool > ring, I'm still seeing failed queries. > > If I understand it correctly, both measures should prevent queries from > ending up in the new DC, but somehow they don't in my situation. > > How is it possible that queries are routed to the new, emtpy data center? > And more importantly, how can I prevent it? > > Thanks, > Tom >
