Could you define what you mean by Casual Consistency and explain why you think you won't have that when using LOCAL_QUORUM? I ask because LOCAL_QUORUM and multiple data centers are the way many of us handle DR, so I'd like to understand why it doesn't work for you.
I'm afraid I don't understand your scenario. Are you planning on building out a new recovery DC *after* the primary has failed, or keeping two DCs in sync so that you can switch over after a failure? Jim On Mon, Dec 14, 2015 at 2:59 PM, Philip Persad <philip.per...@gmail.com> wrote: > Hi, > > I'm currently looking at Cassandra in the context of Disaster Recovery. I > have 2 Data Centres, one is the Primary and the other acts as a Standby. > There is a Cassandra cluster in each Data Centre. For the time being I'm > running Cassandra 2.0.9. Unfortunately, due to the nature of my data, the > consistency levels that I would get out of LOCAL_QUORUM writes followed by > asynchronous replication to the secondary data centre are insufficient. In > the event of a failure, it is acceptable to lose some data, but I need > Casual Consistency to be maintained. Since I don't have the luxury of > performing nodetool repairs after Godzilla steps on my primary data centre, > I use more strictly ordered means of transporting events between the Data > Centres (Kafka for anyone who cares about that detail). > > What I'm not sure about, is how to go about copying all the data in one > Cassandra cluster to a new cluster, either to bring up a new Standby Data > Centre or as part of failing back to the Primary after I pick up the > pieces. I'm thinking that I should either: > > 1. Do a snapshot ( > https://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_backup_takes_snapshot_t.html), > and then restore that snapshot on my new cluster ( > https://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_snapshot_restore_new_cluster.html > ) > > 2. Join the new data centre to the existing cluster ( > https://docs.datastax.com/en/cassandra/2.0/cassandra/operations/ops_add_dc_to_cluster_t.html). > Then separate the two data centres into two individual clusters by doing . > . . something??? > > Does anyone have any advice about how to tackle this problem? > > Many thanks, > > -Phil >
