VirtualBox is a cross-platform virtualization application. it installs on your existing Intel or AMD-based computers, whether they are running Windows, Mac, Linux or Solaris operating systems. Secondly, it extends the capabilities of your existing computer so that it can run multiple operating systems (inside multiple virtual machines) at the same time. So, for example, you can run Windows and Linux on your Mac, run Windows Server 2008 on your Linux server, run Linux on your Windows PC, and so on, all alongside your existing applications. You can install and run as many virtual machines as you like the only practical limits are disk space and memory.
VirtualBox is deceptively simple yet also very powerful. It can run everywhere from small embedded systems or desktop class machines all the way up to datacenter deployments and even Cloud environments.
The techniques and features that VirtualBox provides are useful for
several scenarios:
Running multiple operating systems
simultaneously. VirtualBox allows you to run more than one
operating system at a time. This way, you 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 "virtual" hardware should be presented to each
such operating system, you can install an old operating system such as
DOS or OS/2 even if your real computer's hardware is no longer
supported by that operating system.
Easier software installations.
Software vendors can use virtual machines to ship entire software
configurations. For example, installing a complete mail server
solution on a real machine can be a tedious task. With VirtualBox,
such a complex setup (then often called an "appliance") can be packed
into a virtual machine. Installing and running a mail server becomes
as easy as importing such an appliance into VirtualBox.
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 forward in virtual machine time. You can delete snapshots
while a VM is running to reclaim disk space.
Infrastructure consolidation.
Virtualization can significantly reduce hardware and electricity
costs. Most of the time, computers today only use a fraction of their
potential power and run with low average system loads. A lot of
hardware resources 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.
When dealing with virtualization (and also for understanding the following chapters of this documentation), it helps to acquaint oneself with a bit of crucial terminology, especially the following terms:
- Host operating system (host OS).
This is the operating system of the physical computer on which VirtualBox was installed. There are versions of VirtualBox for Windows, Mac OS X, Linux and Solaris hosts. Most of the time, this User Manual discusses all VirtualBox versions together. There may be platform-specific differences which we will point out where appropriate.
- Guest operating system (guest OS).
This is the operating system that is running inside the virtual machine. Theoretically, VirtualBox can run any x86 operating system (DOS, Windows, OS/2, FreeBSD, OpenBSD), but to achieve near-native performance of the guest code on your machine, we had to go through a lot of optimizations that are specific to certain operating systems. So while your favorite operating system may run as a guest, we officially support and optimize for a select few (which, however, include the most common ones).
- Virtual machine (VM).
This is the special environment that VirtualBox creates for your guest operating system while it is running. In other words, you run your guest operating system "in" a VM. Normally, a VM will be shown as a window on your computer's desktop, but depending on which of the various frontends of VirtualBox you use, it can be displayed in full screen mode or remotely on another computer.
In a more abstract way, internally, VirtualBox thinks of a VM as a set of parameters that determine its behavior. They include hardware settings (how much memory the VM should have, what hard disks VirtualBox should virtualize through which container files, what CDs are mounted etc.) as well as state information (whether the VM is currently running, saved, its snapshots etc.). These settings are mirrored in the VirtualBox Manager window as well as the VBoxManage command line program.
- Guest Additions.
This refers to special software packages which are shipped with VirtualBox but designed to be installed inside a VM to improve performance of the guest OS and to add extra features.
Currently, VirtualBox runs on the following host operating systems:
- Windows hosts:
- Windows XP, all service packs (32-bit)
- Windows Server 2003 (32-bit)
- Windows Vista (32-bit and 64-bit).
- Windows Server 2008 (32-bit and 64-bit)
- Windows 7 (32-bit and 64-bit)
- Windows 8 (32-bit and 64-bit)
- Windows Server 2012 (64-bit)
- Mac OS X hosts:
- 10.6 (Snow Leopard, 32-bit and 64-bit)
- 10.7 (Lion, 32-bit and 64-bit)
- 10.8 (Mountain Lion, 64-bit)
- 10.9 (Mavericks, 64-bit)
- Linux hosts (32-bit and 64-bit). Among others, this includes:
- Debian
- Oracle Enterprise Linux 5, Oracle Linux 6
- Redhat Enterprise Linux 5 and 6
- Fedora Core 6 to 19
- Gentoo Linux
- openSUSE 11.0, 11.1, 11.2, 11.3, 11.4, 12.1, 12.2
- Mandriva 2010 and 2011
- Solaris hosts (64-bit only) Solaris 11 including Solaris 11 Express
Solaris 10 (u8 and higher)