Sun VirtualBox User Manual

Introduction

Sun xVM VirtualBox is a collection of powerful virtual machine tools, targeting desktop computers, enterprise servers and embedded systems. With VirtualBox, you can virtualize 32-bit and 64-bit operating systems on machines with Intel and AMD processors, either by using hardware virtualization features provided by these processorsor even entirely in software, at your option. You can find a brief feature overview in chapter 1.3, Features overview, page 12; see chapter 12, Change log, page 149 for a detailed list of version changes. Virtualization basics With VirtualBox, you can run unmodified operating systems – including all of the software that is installed on them – directly on top of your existing operating system, in a special environment called a “virtual machine”. Your physical computer is then usually called the “host”, while the virtual machine is often called a “guest”. VirtualBox allows the guest code to run unmodified, directly on the host computer, and the guest operating system “thinks” it’s running on a real machine. In the background, however, VirtualBox intercepts certain operations that the guest performs to make sure that the guest does not interfere with other programs on the host. The techniques and features that VirtualBox provides are useful for several scenarios:

• Operating system support. With VirtualBox, one can run software written for one operating system on another (for example, Windows software on Linux) without having to reboot to use it. You can even install an old operating system such as DOS or OS/2 in a virtual machine if your real computer’s hardware is too advanced to be supported.
• Infrastructure consolidation. Virtualization can significantly reduce hardware and electricity costs. The full performance provided by today’s powerful hardware is only rarely really needed, and typical servers have an average load of only a fraction of their theoretical power. So, instead of running many such physical computers that are only partially used, one can pack many virtual machines onto a few powerful hosts and balance the loads between them. WithVirtualBox, you can even run virtual machines as mere servers for the VirtualBox Remote Desktop Protocol (VRDP), with full client USB support. This allows for consolidating the desktop machines in an enterprise on just a few RDP servers, while the actual clients only have to be capable of displaying VRDP data.
• Testing and disaster recovery. Once installed, a virtual box and its virtual hard disk can be considered a “container” that can be arbitrarily frozen, woken up, copied, backed up, and transported between hosts. On top of that, with the use of another VirtualBox feature called “snapshots”, one can save a particular state of a virtual machine and revert back to that state, if necessary. This way, one can freely experiment with a computing environment. If something goes wrong (e.g. after installing misbehaving software or infecting the guest with a virus), one can easily switch back to a previous snapshot and avoid the need of frequent backups and restores.

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