The fires of hot topics are usually stoked with hype, but in the case of storage virtualization, the topic actually exceeds the hype. Let me explain why.
It's not surprising that many vendors are jumping on the virtualization bandwagon by recasting their legacy products as virtualization engines of some form. What is surprising is that these vendors may be more correct in doing so than they may have imagined. Even a rigid definition of virtualization is broad enough to include many of the storage products of the last decade. Unfortunately, with everyone claiming to own virtualization, the overall message has been diluted.
Storage virtualization is a new architecture for storage networks, using virtual mapping of data files onto a network of storage devices, according to the IBM Redbook report Storage Networking Virtualization: What's it all about? (While the report does exhibit some bias toward IBM products, it also presents a good overview of the issues and benefits of virtualization in a network storage environment.)
By this definition, a massive amount of technology can huddle under the storage virtualization umbrella, including RAID, Fibre Channel to SCSI bridges, and network-attached storage (NAS).
Despite the fact that many people claim that aggregation isn't virtualization, I disagree. In my opinion, aggregation is a flavor of virtualization since it changes the physical presentation of storage to a logical representation. However, aggregation may be the least interesting or challenging form of virtualization.
In case you're beginning to wonder why virtualization is such an important topic, consider this: The difficulties associated with management of the ever-growing storage assets in the enterprise continue to be serious problems. The only hope we have of understanding a system that is already complex and growing continuously is to create abstractions. Storage virtualization provides the abstractions that will make complex storage systems manageable. By reducing the required headcount for managing storage (or holding the headcount steady while demand for storage increases), virtualization will greatly decrease the total cost of ownership (TCO) for storage.
It will be interesting to see what sort of standards can be produced for storage virtualization. Look at how virtualization fits into the overall storage architecture, and you'll discover that many of the interfaces are already well defined. The logical presentation and the physical storage assets define the high and low ends of the architecture, respectively. That leaves service and peer interfaces without standards for storage virtualization. There are many examples of standards for service interfaces but precious few standards for peer interfaces. The storage virtualization vendors may well blaze a trail for the computer industry if they choose to address standards for peer interfaces.
Storage virtualization from CNET
For more information on storage virtualization check out this white paper for a look at the opportunities, challenges, and limits of storage virtualization, both as conceptual architecture and as a real technology to be implemented