1. VMAX is modular built storage subsystem but who say that this is a benefit to the end user. As opposed to cache centric monolithic control unit, adding modules most probably will increase the response time on some I/O. See my presentation from SNW 2010. Such structure require frequent tunings and redistribution of data.
2. Feedback from one of my customers: VMAX can't scale not disruptively. Updating cache means taking-off the side with the host channels. The customer must provide 2nd path.
3. Fujitsu Eternus series support the same functionality and storage management across the the whole line. VMAX, VNX supports different functionality. The VMAX is controlled by Enginuity, the block part of VNX by FLARE sitting on Windows and the file by DART -3 different remote copy techniques, 3 different flash copy, etc.
4. There is nothing virtual in the Virtual Matrix Interface - it is RapidIO protocol which is competition to InfiniBand but it is very real.