I've begun working on a reference project intended to provide guidance on configuring and operating a modest Cassandra cluster of about 18 nodes suitable for the economic study, demonstration, experimentation and testing of a Cassandra cluster.
The slender cluster would be designed to be as inexpensive as possible while still using real world hardware in order to lower the cost to those with limited initial resources. Sorry no Raspberry Pi's for this project. There would be an on-premises version and a cloud version. Guidance would be provided on configuring the cluster, on demonstrating key Cassandra behaviors, on files sizes, capacity to use with the Slender Cassandra Cluster, and so on. Why about eighteen nodes? I tried to figure out what the minimum number of nodes needed for Cassandra to be Cassandra is? Here were my considerations: . A user wouldn't run Cassandra in just one data center; so at least two datacenters. . A user probably would want a third data center available for analytics. . There needs to be enough nodes for enough parallelism to observe Cassandra's distributed nature. . The cluster should have enough nodes that one gets a sense of the need for cluster wide management tools to do things like repairs, snapshots and cluster monitoring. . The cluster should be able to demonstrate a RF=3 with local quorum. If replicated in all three data centers, one write would impact half the 18 nodes, 3 datacenters X 3 nodes per data center = 9 nodes of 18 nodes. If replicated in two of the data centers, one write would still impact one third of the 18 nodes, 2 DC's X 3 nodes per DC = 6 of the 18 nodes. So eighteen seems like the minimum number of nodes needed. That's six nodes in each of three data centers. Before I get too carried away with this project, I'm looking for some feedback on whether this project would indeed be helpful to others? Also, should the project be changed in any way? It's always a pleasure to connect with the Cassandra users' community. Thanks for all the hard work, the expertise, the civil dialog. Kenneth Brotman
