With Longhorn expected by year’s end, Microsoft’s server-virtualization play—Viridian—will arrive soon as well. But it will be short of a few key features. IT press and blog critics were quick to bash Microsoft over the pulled features, especially in the light of ongoing delays for Longhorn. But the move is typical of Microsoft’s new-product strategies (aim for the mainstream; embrace and extend) and would seem to impact only the very earliest of early adopters. Microsoft is competing with pure-play virtualization vendors, notably VMware and open-source project XenSource.

The changes include no Live Migration, which enables IT to move VMs from one physical machine to another; no hot-add resources (including storage, networking, memory and processors); and a support limit of 16 cores/logical processors. The truth is, the majority of the virtualization market isn’t baked yet. Shops currently relying on industrial-strength VMware will continue to run that software after Longhorn is released. Longhorn virtualization will be used by new VM customers and adopters because it will be bundled in the OS and should be well-integrated in terms of both setting up and running it.