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This is a guest post by Tommaso Barbugli the CTO of getstream.io, a web service for building scalable newsfeeds and activity streams.
In January we migrated our entire infrastructure from dedicated servers in Germany to EC2 in the US. The migration included a wide variety of components, web workers, background task workers, RabbitMQ, Postgresql, Redis, Memcached and our Cassandra cluster. Our main requirement was to execute this migration without downtime.
This article covers the migration of our Cassandra cluster. If you’ve never run a Cassandra migration before, you’ll be surprised to see how easy this is. We were able to migrate Cassandra with zero downtime using its awesome multi-data center support. Cassandra allows you to distribute your data in such a way that a complete set of data is guaranteed to be placed on every logical group of nodes (eg. nodes that are on the same data-center, rack, or EC2 regions...). This feature is a perfect fit for migrating data from one data-center to another. Let’s start by introducing the basics of a Cassandra multi-datacenter deployment.
Cassandra, Snitches and Replication strategies