5.5.3 Hypervisors and Guest Operating Systems

Type 1 Hypervisors A bare-metal hypervisor, also called a Type 1 hypervisor, is special software that works directly on a computer without needing Windows or any other operating system first. It's great because it lets virtual machines (VMs) run incredibly well without a lot of interference. Since there's no main operating system in the way, the computer can give out more power to the VMs. It's also safer because there's less chance for viruses or malicious software to get in. Virtual Machine Manager Windows 7 Guest OS Windows Server Guest OS Hardware Type 2 Hypervisors On the other hand, a Type 2 hypervisor is similar to a regular program you run on your computer, like a game or a word processor. It needs the main operating system, like Windows or macOS, to work. It does a lot of the same things as Type 1, but it uses more of the computer's resources to get started. Ubuntu Guest OS DOS Guest OS Operating System Guest Operating Systems The guest operating system (OS) is the term for the operating system that runs inside the virtual environment. This might surprise you, but sometimes people need to use an older version of Windows for certain things. And when it comes to Linux, there are hundreds of versions, or "distros," that can be set up in these virtual machines.What's most common, though, is putting several Linux or Windows servers inside of one physical computer. This is handy because servers have a ton of power. They often have more than one CPU with multiple cores (which is like having more than one brain), a lot more memory than a typical computer, and more storage space as well. With virtualization, you can divide up this power among multiple guest OSs. If you wanted, you could even have Windows running inside another Windows, kind of like Russian nesting dolls where one fits inside the other. Guest OS Uses Let's try to understand why this is so great. Your computer can pretend to be many computers at once. Now, each pretend computer can do a different job. For example, one might keep all the office files together for you and your coworkers, another might keep track of all the printers, and a third might handle all the emails. These pretend computers can each use a different OS if a certain system is better for a certain thing—Windows Server on one and Linux Ubuntu on another, for example.It's important to make clear that these computers don't affect each other. That's one huge advantage. If one gets a virus or stops working, it won't cause problems for the others. They're like neighbors who are walled off in their own apartments. What happens in one doesn't affect the others. A break-in in apartment 307 doesn't mean anything will be missing from apartment 308 next door.Also, if you need to move one of these virtual host OS computers over to a physical computer, it's pretty easy to do since it's just a collection of files and folders. As long as the new computer is running the same virtualization software, like VMware or Virtual Box, you can move things with very little effort.