We recently had a conversation with DataStax regarding their DataStax Enterprise product, which got us to thinking a little about the nature of Big Data and Cloud. DataStax is the company behind the Open Source Cassandra NoSQL database. It provides technical direction and the majority of committers to the Apache Cassandra project.
Given that vSphere provides significant benefits in terms of cost savings and business agility, those benefits are tied to and constrained by the ability of vSphere to provide backward compatibility with existing legacy enterprise systems. This backward compatibility makes it impossible for vSphere to provide infinite horizontal scalability. Moving to the same architecture as the most highly scaled out public cloud vendors provides for a more radical set of benefits, but at the cost of breaking backward compatibility for many applications.