Using virtualization and VHDs has a number of advantages over standard operating system installations:
• Better resource utilization—One of the big issues in many companies, large and small, is buying too many computers to perform multiple tasks. Virtualization essentially eliminates this problem because you can buy a single computer and use it to handle multiple requests. Need a separate server for your financials? No problem. How about a separate server for your customer database? Not a problem. Virtualization allows you to create these servers on-the-fly, without having to buy and configure new hardware each time a new request comes up.
• Speed of deployment—Creating a new virtual server is a simple task, taking only a few minutes. You can go from “I need a new machine to do this task” to “it’s done” in under 10 minutes, including the time to create the virtual server, configure it, load a fully configured template, configure that with specific information such as name and IP, and test it to make sure that it’s ready for use. Compare that with having to buy a new PC, configuring the new PC, and getting it up and running. In the time it would take you to unpack your new machine from its boxes, you can have your new virtual server up and running.
• Lower operating costs—Frankly, virtual systems are cheaper to run. They require less power and don’t take as much effort to cool. Which means that in addition to not having to buy a new machine each time, you don’t have to pay as much to run it, either.
• Upgrades and migration—Suppose that you have a particular virtual server that is consuming an expanding amount of resources— more RAM, more hard disk space, more everything—and you need to upgrade it. If it were a physical server, you’d have the problem of getting the new machine up, then moving everything cleanly, then shutting down the old server and making sure that the transition went smoothly. With a virtual machine, that problem essentially goes away. Yes, you’ll need the new hardware, but by transferring a copy of the virtual server across to the new machine, you can migrate the entire operating environment in just a matter of minutes. You can use the same technique for upgrades. Just shift your VM from one machine to another and then take the old machine offline while you perform your maintenance.
• Deploying standard systems—One issue we’ve always considered a real nuisance is deploying a “standard” system image when we bring up a new computer. First you have to load the operating system. Then you have to catch up all the system patches. Next you have to run the entire checklist of “is this software loaded,” and configure it for your company, and make sure that is all up-to-date and patched. It can take hours. With VHDs, this becomes incredibly easy. After you’ve created a template system, all you have to do is copy the VHD for the template to some form of storage, such as a DVD, a thumb drive, or a network drive. The next time you need to load a system, you can bypass the bulk of your problem by loading the VHD directly to the disk and launching it.
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To illustrate how system images work, we used this feature while we were developing this topic, testing on one machine, creating on another, and shooting the artwork on a third, all using the same set of virtual machine files.
• Backups—Another aspect of virtualization that we’ve found to be tremendously useful is in backing up systems after they’re configured. Because the entire operating system image is a single file, it’s quite simple to store a version of that entire file elsewhere, for easy recovery. This is useful in a number of ways. First, it lets you keep a complete snapshot of a system—for example, your desktop. Second, it’s also useful when you have to set up and tear down systems on a regular basis—such as when you need a test environment or if you need environments for a training class.
