From the course: Career Essentials in System Administration by Microsoft and LinkedIn

What is virtualization?

From the course: Career Essentials in System Administration by Microsoft and LinkedIn

What is virtualization?

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- In technical terms virtualization uses software to create an abstraction layer over computer hardware that allows the hardware elements of a single host computer to be divided into multiple virtual ones. That may be a bit too technical. So let me explain a virtual machine to beginners. Take any computer running, any operating system install an application on that computer, take some of the processing power, some of the Ram and hard drive space and allow another operating system to borrow it. The second operating system runs on top of the first one. The computer running this application is now called the host, and any virtual machine computers running on top of the host are now referred to as guests. The only limit to the amount of virtual machines running on the host is based on the amount of extra processing power Ram and hard drive space that is available for the guests. You'll also possibly need licenses for each guest unless they are open source like Linux. There are two types of virtualization type one and type two hypervisors. A type one is the most preferred because it has direct access to the hardware previously mentioned. Type two hypervisors rely on the operating system first so any virtualization has to work with the underlying OS to manage calls to the hardware. This can cause latency and potential crashes. Because of this it's typically not used in a production environment. A great example of this would be VMware. VMware has a type one hypervisor called ESXi, and a type two hypervisor called VMware workstation. Workstation installs on top of an OS such as Windows, Macintosh, or Linux. ESXi installs using a very light version of a Linux OS, and is managed from another computer. Other examples of a type one hypervisor are HyperV from Microsoft, KVM, Zen, and Oracle VM. Type two examples also include virtual box Q E M U and parallels. I recall prior to 2008, all of our computers were on physical machines. This meant needing a lot of electricity, cooling power and a lot of servers. Then we started installing virtual machines and buying less but more powerful servers. We could then replace four racks of servers with just a couple of servers that didn't even take up half of a server rack. IBM saw this trend coming and sold much of their server division to Lenovo, and Dell went from a public company to a private one. There just wasn't much money in servers anymore. However, Microsoft saw a boost in their business by selling more licenses for each virtual machine, and eventually creating their own VM business in the cloud called Azure. Amazon web services also created their own cloud site. Other companies did something similar, but these two companies have the majority share in the cloud hosted business. Virtualization has completely changed the landscape for CIS admins. There's now less hardware and more software to manage. This caused a shift in the type of education a CIS admin required to earn a top paying IT job.

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