Operating system virtualization is a method of altering a standard operating system so it may handle multiple users all at the same time. These individual users would not have any interaction with one another. Their information would also remain separate, even though they are using the same system. While this technology has several uses, the most common uses are in hosting situations and server consoladation. With operating system virtualazation, a single system is set up to operate like several individual systems. The virtualized system is set up to simultaneously except commands from different users. These commands remain separate from one another; the results and impact of any given command has no effect on commands from others. This division of resources should be transparent to the user, they shouldn’t be able to tell whether they are on a virtual system or not. A common example of this process is the logout command. On a normal computer system, logging out of the operating system will suspend user input until required by the logout system or the user logs back in. In a system using operating system virtualization, when one user logs out the operating system just logs out the single user, but the rest of the users are unaffected.
There are two common circumstances where operating system virtualization is used, hosting environments and server consolidation. Web hosting companies, e-mail storage systems and other account-based hosting systems, often use virtual systems. Since the users of these types of systems require very few resources it is possible for many people to log on at once without taxing the system. Each user operates inside their own environment without interacting with, or seeing the resources of, other users. The second common area where a user may encounter operating system virtualization is on a consolidated server. As computer systems increase in power, one new server may be able to take the jobs of several older ones. In this case, it is possible to combine all the server resources onto the new machine. Since the old servers were separate, it is often necessary to maintain the isolation used by the original systems. In both of these areas, multiple users that have no relationship to one another have to use the same server. This is one of the most common aspects of operating system virtualization. If the users were part of the same group, then they could coexist and share resources. The only reason to keep them separate is when the users have no relationship with one another and have no reason to combine systems.