There are many enhancements and new features that are part of VMware vSphere V5.0 from a storage and I/O perspective (See VMware vSphere v5 and Storage DRS posts). One of those enhancements is a new Application Programming Interface (API) called VASA (vSphere Aware Storage API) which joins other VMware vSphere APIs some of which are shown in table 1. Note that there is a three letter acronym (TLA) shown in table 1 that is part of the VMware vSphere 5.0 release that can be confused with VASA called VSA (VMware Storage Appliance) however for now, let’s leave VSA for a future discussion.