DataStax Academy FAQ

DataStax Academy migrated to a new learning management system (LMS) in July 2020. We are also moving to a new Cassandra Certification process so there are changes to exam bookings, voucher system and issuing of certificates.

Check out the Academy FAQ pages for answers to your questions:


question

rashokkumartce_193569 avatar image
rashokkumartce_193569 asked ·

How do we define replication for a cluster that's distributed across regions?

While creating keyspaces we are specifying replication factor for each data centers, what if nodes are spread across regions how do we specify replication ?

If nodes are spread across regions, say set of nodes in Europe and set of nodes in US form a cluster. Do such clusters exist or is there any possibility ? If yes, how do we define replication while creating keyspaces?

replication
10 |1000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 1.0 MiB each and 10.0 MiB total.

1 Answer

Erick Ramirez avatar image
Erick Ramirez answered ·

The physical location of data centres don't matter where replication is concerned.

Let me illustrate with this example where a cluster has:

  • nodes in a DC in UK
  • nodes in a DC in France
  • nodes in a DC in the US
  • nodes in a DC in Singapore

The keyspace replication can be defined as:

CREATE KEYSPACE globalks
  WITH REPLICATION = {
    'class': 'NetworkTopologyStrategy',
    'UK_DC': 3,
    'FR_DC': 3,
    'US_DC': 3,
    'SG_DC': 3
  };

And yes, lots of organisations have their clusters distributed across geographies. Cheers!

Share
10 |1000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 1.0 MiB each and 10.0 MiB total.