cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Jim Ancona <>
Subject Re: Replicating Data Between Separate Data Centres
Date Mon, 14 Dec 2015 21:06:00 GMT
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?


On Mon, Dec 14, 2015 at 2:59 PM, Philip Persad <>

> 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 (
> and then restore that snapshot on my new cluster (
> )
> 2. Join the new data centre to the existing cluster (
> 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

View raw message