A recent article in Information Week discusses how Credit Suisse has been very successful implementing virtualization in the data center and how they view the desktop as the next area of opportunity. By virtualizing desktops and bringing them into the data center, Credit Suisse hopes gain the ability to quickly re-provision desktops in response to changing user needs. But at what cost?
Depending on how many users Credit Suisse has, this means moving the processing from thousands of independent computing elements into the data center. Out in the enterprise, power and cooling is abundant and there is no issue with rack space. Perhaps they have ample space in their data centers.
What about user experience? There is something to be said about moving the processing as local to the user as possible. Some applications lend themselves to be hosted centrally and accessed via a browser or portal interface. Other applications including multimedia, unified communications and complex user interfaces are better served at the endpoint device to enable the best responsiveness and/or mobility.
Virtualization is a great technology and it definitely creates new possibilities in terms of OS and application portability. This might be the right solution for Credit Suisse, given their user needs, sets of applications and data center configurations. Who can blame them for wanting to build on their past success. However, there is a bigger picture to consider the correct balance of computing models for particular usage models.
I recently helped with some testing to evaluate VHD and how it faired on a few different server configurations. The results were interesting. We found exactly what you mention regarding the appropriate workloads. Some worked well, some did not.
The really interesting thing for me was the fledgling nature of this type of environment. Virtualization as a technology and industry has not yet evolved in the area of widely accepted test methodologies. Given the new possibilities you mention, a lot of people are coming up with their own way to evaluate configurations. Look up vConsolidate, VMMark, and the pending SPEC Virtualization Benchmark. They are a great start at test and benchmark solutions, but they are effectively testing the same thing; Consolidation of workloads onto a single server. There are many more ways to implement a virtualized environment where these tests do not evaluate. More maturity in benchmarking and simply having tools to evaluate configurations is necessary.
Defining a workload for the VHD testing I was involved in was simply our definition of a light vs. heavy user load. It would be interesting to see what Credit Suisse's workloads were and if they truly mimic actual user use cases (I have no reason to believe they wouldn't.) We checked with other industry leading companies in this area and they effectively did the same. As example, VMWare also appears to have drawn a line in the sand for testing their VDI solution in this report: http://www.vmware.com/pdf/vdi_sizing_vi3.pdf
My last comment is to reiterate your 'warning' about finding an appropriate use model. Virtualized environments are not new, but their popularity is certainly refreshed. As is with most newly popular things, the buzz may exceed delivery in some areas.