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From Anuj Wadehra <>
Subject Re: Multiple Cluster vs Multiple DC
Date Tue, 05 May 2015 12:43:51 GMT
Multiple DC is usually useful in case u need Geo Redundancy or have distributed workload. Do
u have these clusters at same physical location? If 3 nodes are at diff locations dont u need
geo red for disaster ? Whats ur RF for cf? 



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From:"Alain RODRIGUEZ" <>
Date:Tue, 5 May, 2015 at 2:50 pm
Subject:Multiple Cluster vs Multiple DC


tl;dr : How to choose between having a Cluster with 2 DC and having 2 separate clusters as

"cluster_name: mycluster

KS1 {DC1: 3, DC2: 0} and KS2 {DC1: 0, DC2: 3}"


"cluster_name: cluster1

KS1 {DC: 3}


cluster_name: cluster2

KS2 {DC: 3}"

We can use distinct columns and row to keep distinct entries, depending on sharding, locallity
and query I know how to model this.

At a higher level we have CF, Keyspace. Basically, to chose if I want to choose between a
CF or a Keyspace, I ask myself if this table has a logical interest in beeing separated from
existing keyspaces. This mainly depend on RF I want on each DC or if the table has a very
specific workload that would need a specific attention and tuning.

But when to decide having multiple cluster instead of multiple DC with each DC its Keyspace

Thanks for any enlightening you can give me around this.



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