Thought you might like to read this thread from Simon Crosby…
Whither the Venerable OS?
Virtualization challenges many established IT “truths” from the heyday of x86 scale-out. Nowhere is this more apparent than in the identity crisis facing the major OS vendors in the context of virtualization.
VMware’s (initial 
) success in infrastructure virtualization, and the rapid gains XenServer is making (we added ~25,000 customers in the last quarter) appears to confirm that IT managers view the virtualization of their datacenter infrastructure as a platform property completely independent of the workloads that use it, but most OS vendors believe that adding virtualization to the OS should lead to success both as an OS and as a virtual infrastructure platform.
To be perfectly clear, I don’t for a moment think that Hyper-V in Windows, or Xen or even KVM in Linux are bad hypervisors. They aren’t. Hyper-V R2 is by all accounts excellent, and Xen is of course fabulous. But a great hypervisor is not a great virtual infrastructure platform. The key is the rest of the infrastructure – the abstractions of storage, networking, compute that enable resource pooling, multi-tenancy, high availability, dynamic workload balancing and all of the other benefits that accrue from a virtualized infrastructure.
Virtualization as property of the infrastructure is nowhere more obvious than in Infrastructure as a Service (IaaS) clouds such as Amazon’s EC2 and Virtual Private Cloud VPC, RackSpace’s Cloud Serversâ„¢ and Softlayer’s CloudLayerâ„¢. Virtualization provided by the user’s OS is of no benefit in the cloud since the cloud platform already includes it. Moreover IaaS clouds offer a richer notion of virtualization than that afforded by a hypervisor – they virtualize, isolate and secure server, storage and networking resources across pools of hardware resources, to deliver a rich set of infrastructural services and SLAs that are necessarily not OS-specific.
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