Integrating solid state storage as a VMware cache isn’t a trivial task. In fact, it’s become the core challenge for some of the best minds in storage, and few real answers have yet emerged. This will be a primary area of focus for me and others who watch and comment on virtualization and enterprise storage!
Perhaps the previous discussion of spindles left you exhausted, imagining a spindly-legged centipede of a storage system, trying and failing to run on stilts. The Rule of Spindles would be the end of the story were it not for the second horseman: Cache. He stands in front of the spindles, quickly dispatching requests using solid state memory rather than spinning disks. Cache also acts as a buffer, allowing writes to queue up without forcing the requesters to wait in line.