Major OS or software upgrades can be exciting for a system administrator, but they can also be a little frightening. What if something breaks? What if you lose everything and have hours or even days of down time? This can be especially troubling if you have web applications and are upgrading the underlying software that runs it (i.e. Apache, PHP, or MySQL).
Fortunately, there is a way you can safely test upgrades without actually installing. It is called virtualization. Although there are plenty of other reasons to use virtualization, testing is certainly a compelling reason to give it a try. All you need is a computer and some virtualization software.
Some virtualization software, such as VMware, costs money and is proprietary. Others, like Virtualbox, are free and open source. Still others may be either but are also integrated into server operating systems. Examples include KVM for Linux and Hyper-V, which comes with Windows Server 2008, but even if your OS does not come with one of these, you can still install them.
Once installed, you can then use the virtualization software to install an instance of your dedicated server’s OS within a safe environment. You can then perform all of the web application and upgrade testing you want with realistic results. With virtualization you can use operating systems within the virtual machine that are different from the physical machine. For example, you can run a Linux server instance inside of your Windows computer, or an instance of Windows Server 2008 inside of Windows 7.