Similar Architecture
With all of the marketing hype aside, probably the best reason for running Windows Vista and Longhorn Server together is that they are essentially the same operating system. To understand what I am talking about, you need to look at Microsoft’s history of operating systems. When Microsoft released Windows NT Server 4.0, they also released Windows NT Workstation at the same time. The only difference between the two operating systems was a registry setting. By altering one registry setting, you could turn Windows NT Workstation into Windows NT Server, and vice versa.
Fast forward a few years, and Microsoft did something similar with Windows 2000. Windows 2000 Server and Windows 2000 Professional were developed simultaneously and contained nearly identical kernels.
Microsoft’s next server release was Windows Server 2003. Windows Server 2003 was developed separately from Windows XP (to the best of my knowledge), and there are some significant differences between the two operating systems.
When Microsoft decided to develop Windows Vista, they went back to their roots. Windows Vista and Longhorn Server were developed simultaneously, using the same operating system kernel. In fact someone from Microsoft explained to me that differences in the two operating systems (aside from applets, consoles, etc.) were only introduced into the code after Windows Vista released the Beta 2 stage of development. This ensured that the underlying code base was stable before server specific code was introduced.
Being that Longhorn Server and Windows Vista share a common kernel and user interface (although Aero is disabled by default in Longhorn Server), it only makes sense that the two operating systems would work well together. However, a more compelling reason for deploying Longhorn Server and Windows Vista together is that doing so can reduce your support costs.
Think about it for a minute. If both operating systems share a common core, then you don’t really have to worry about training your support staff on two separate operating systems. Yes, there are definitely server specific components that your support staff will need to learn about, but eighty to ninety percent of code is going to be the same for both operating systems. That means that if your support staff knows how to fix a problem in Vista then there is a good chance that they will also know how to fix the problem if it should occur on a Longhorn server.
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