There seems to be an inaccuracy in the article comparing scale between Aerospike and Cassandra. Scale comes in many ways. One is scaling to handle higher data sizes - DataStax/Cassandra may handle higher DATA VOLUMES that I am not aware of but that would not apply to the in-memory version, definitely. However, if scale is about transaction THROUGHPUT at LOW LATENCY, Aerospike is far and away the market leader.
What could be higher scale than real-time platforms like AppNexus, BlueKai - the third largest DMP that Oracle just acquired - eXelate, The Trade Desk, Chango and others that are managing terabytes of data at over 1 Million TPS at steady state (>30% writes), with predictable response times 99% in 3-5ms? All these are Aerospike customers.
Also, In-Memory has existed in NoSQL for a long time. Aerospike (previously named Citrusleaf) has been in continuous production since early 2010 on various in-memory configurations (in addition to flash/ssd based configurations). I am sure other NoSQL products have had in-memory also for much longer, like Redis, for example.
Srini V. Srinivasan
Founder, VP Engineering and Operations