By way of comparison, you could say that virtual storage is taking a path similar to server virtualization. Round one was about consolidation, i.e., putting multiple virtual machines (VMs) on one physical server to improve server utilization. In server virtualization, round two was about moving VMs from one physical server to another for load-balancing or other reasons. On the storage side, round two leads to new approaches to managing storage-on-demand, dynamic resizing and relocation of workloads and improved availability.
Now federation enables cooperation among pools of server and storage resources necessary to bring about IT as a service through dynamic application availability and data movement where even global distances are not a barrier.
That sounds wonderful, so why hasn't federation on a global basis happened before? In limited senses, it has, but up to now, the general and universal problem of actually how to do virtual storage on a global basis, rather than just think about it, had not been solved. There have been three challenges to coming up with a global solution: latency, bandwidth and consistency. As EMC points out, location matters in order to improve protection and availability of information as well as optimize costs and utilization. In other words, EMC's view is that it is necessary to exploit distance if we are going to get to the "this changes everything" stage. Yet those three challenges -- latency, bandwidth and consistency -- get in the way of a general solution.
Still, the answer to the challenge has been known for some time -- use caching. The problem in getting to the answer is something called "distributed cache coherency," which addresses the three challenges of latency, bandwidth and consistency. In fact, the problem has been around for a long time (for example, see a technical paper "Design and implementation of a distributed cache coherence protocol," published in April 1990 -- 20 years ago!). That indicates that the problem has been an intractable one
Gelsinger really didn't go into any detail on how EMC has solved this problem or what kind of intellectual property (IP) they have derived as a result. However, the company is confident that it has solved the distributed cache coherency problem. EMC is now publicly committed to being able to build practical storage federation using virtual storage on top of distributed cache coherence. Gelsinger used the meeting to make statements of direction rather than product announcements. However, without making a formal product announcement, he stated that an appliance-based product will be the first fruit of EMC's virtual storage concept. One might expect its debut in May at EMC World in Boston.
