Cassandra and Aerospike, the one million TPS war

Dec 2nd, 2011, Netflix first put one million writes on 288 EC2 m1 extra large nodes, triple-replicate. $0.078 per million writes.
The wars began!
http://techblog.netflix.com/2011/11/benchmarking-cassandra-scalability-on.html

July 19th, 2012, Netflix tested Cassandra with 12 SSD-based EC2 nodes, triple-replicate. $0.013 per million writes.
http://techblog.netflix.com/2012/07/benchmarking-high-performance-io-with.html

March 20th, 2014. 330 Cassandra nodes with Google's GCE. No hardware spec.
http://googlecloudplatform.blogspot.sg/2014/03/cassandra-hits-one-million-writes-per-second-on-google-compute-engine.html

December 3rd, 2014. Aerospike made it with 50 nodes.  $0.01 per million writes.
http://www.aerospike.com/blog/1m-wps-6x-fewer-servers-than-cassandra

To be continued...