1 First steps
You can find a summary of VirtualBox’s capabilities in chapter 1.3, Features overview, page 12. For existing VirtualBox users who just want to see what’s new in this release, there is a detailed list in chapter 12, Change log, page 167.
1.1 Why is virtualization useful?
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 or a Mac) without having to reboot to use it. Since you can configure what kinds of hardware should be presented to each virtual machine, 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 no longer supported by that operating system.
•Testing and disaster recovery. Once installed, a virtual machine and its virtual hard disks 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.
Any number of snapshots can be created, allowing you to travel back and for- ward in virtual machine time.
•Infrastructure consolidation. Virtualization can significantly reduce hardware and electricity costs. Servers today typically run with fairly average low system loads and are rarely used to their full potential. A lot of hardware potential as well as electricity is thereby wasted. 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.
With VirtualBox, 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.
•Easier software installations. Virtual machines can be used by software ven- dors to ship entire software configurations. For example, installing a complete mail server solution on a real machine can be a tedious task. With virtualization it becomes possible to ship an entire software solution, possibly consisting of many different components, in a virtual machine, which is then often called an “appliance”. Installing and running a mail server becomes as easy as importing such an appliance into VirtualBox.
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