Hi Bryan, It does not generate any errors. A query for a specific row simply does not return the row if it is sent to a node in the new DC. This makes sense, because the node is still empty.
On Thu, Sep 3, 2015 at 9:03 PM, Bryan Cheng <br...@blockcypher.com> wrote: > This all seems fine so far. Are you able to see what errors are being > returned? > > We had a similar issue where one of our secondary, less used keyspaces was > on a replication strategy that was not DC-aware, which was causing errors > about being unable to satisfy LOCAL_ONE and LOCAL_QUORUM quoroum levels. > > > On Thu, Sep 3, 2015 at 11:53 AM, Tom van den Berge < > tom.vandenbe...@gmail.com> wrote: > >> Hi Bryan, >> >> I'm using the PropertyFileSnitch, and it contains entries for all nodes >> in the old DC, and all nodes in the new DC. The replication factor for both >> DCs is 1. >> >> With the first approach I described, the new nodes join the cluster, and >> show up correctly under the new DC, so all seems to be fine. >> With the second approach (join_ring=false), they don't show up at all, >> which is also what I expected. >> >> >> On Thu, Sep 3, 2015 at 8:44 PM, Bryan Cheng <br...@blockcypher.com> >> wrote: >> >>> 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 >>>> >>> >>> >> >
