DataStax Community Edition is a free software bundle from DataStax that combines Apache Cassandra with a number of developer and management tools provided by DataStax, which are designed to get someone up and productive with Cassandra in very little time. DataStax Community Edition is provided for open source enthusiasts and is not recommended for production use as it is not formally supported by DataStax’ production support staff.
DataStax Enterprise is the commercial product offering from DataStax that is designed for enterprise-class, production usage that combines Apache Cassandra with real-time analytics capabilities and smart mixed workload management. DataStax Enterprise also provides full 24×7 production support, consultative assistance, certified maintenance updates, and much more.
Cassandra has been built from the ground up to be a fault tolerant, peer-to-peer database that offers no single point of failure. Cassandra can automatically replicate data between nodes to offer data redundancy. It also offers built-in intelligence to replicate data between different physical server racks (so that if one rack goes down the data on other racks is safe) as well as between geographically dispersed data centers, and/or public Cloud providers and on-premises machines, which offers the strongest possible uptime and disaster recovery capabilities:
Cassandra does not use a master/slave architecture, but instead uses a peer-to-peer implementation, which avoids the pitfalls, latency problems, single point of failure issues, and performance headaches associated with master/slave setups.
Replication is the process of storing copies of data on multiple nodes to ensure reliability and fault tolerance. When you create a keyspace in Cassandra, you must decide the replica placement strategy: the number of replicas and how those replicas are distributed across nodes in the cluster. The replication strategy relies on the cluster-configured snitch to help it determine the physical location of nodes and their proximity to each other.
The total number of replicas across the cluster is often referred to as the replication factor. A replication factor of 1 means that there is only one copy of each row. A replication factor of 2 means two copies of each row. All replicas are equally important; there is no primary or master replica in terms of how read and write requests are handled.
Replication options are defined when you create a keyspace in Cassandra. The snitch is configured per node.