Steve, both XtremIO and VNX are great products with great use cases. Everything about XtremIO - from management to inline data reduction, to data protection to HA is custom designed for flash. On the other hand VNX has unique capabilities that XtremIO does not have e.g. file protocol support. EMC customers will always have a deep and broad portfolio of products to choose from to fit their use cases and maximize their investment.
there are 2 statement in EMC's 2 separate documents
so, what on earth determin the physical address?