Server Virtualization Is Changing Datacenter Architectures

Although multitasking OSs enable running multiple applications and OS services (such as a Web server or directory service) simultaneously on the same physical computer, most system architects avoid this practice because of the potential for software conflicts and to eliminate the risk of disrupting one function while performing maintenance on the other. In fact, many software vendors won’t even support their product if it is installed on the same server with other applications. Unfortunately, this practice has led to massive server proliferation, with only large organizations able to generate workloads large enough to permit a single application to fully exploit the advanced features and economies of scale associated with high-end servers.

Another problem with modern server OSs, particularly Windows, is that each OS’s settings are dependent on the physical hardware and each application stores its settings in the OS. These linked couplings create big problems for system administrators: they cannot easily move applications from one server to another; cannot move the entire set of OS and application software to a different physical hardware (unless it is nearly identical); and cannot fully restore a backup tape to different physical hardware in the event of a disaster.