Screenshot of VirtualBox v4.1.8 running a copy of Kubuntu 11.04 on Windows 7. The window to the left is VirtualBox virtual machine manager and the one to the right is the desktop of Kubuntu
|Initial release||January 15, 2007|
|Stable release||4.2.12 (April 12, 2013[±])|
|Preview release||4.2 RC 3 (August 29, 2012[±]0.3.20)|
|Operating system||Microsoft Windows, Mac OS X, Linux and Solaris|
|Size||40 – 90 MB depending on platform|
|License||Base Package: GNU General Public License version 2 (Optionally CDDL for most files of the source distribution), "Extension Pack": PUEL|
Oracle VM VirtualBox (formerly Sun VirtualBox, Sun xVM VirtualBox and innotek VirtualBox) is an x86 virtualization software package, created by software company Innotek GmbH, purchased in 2008 by Sun Microsystems, and now developed by Oracle Corporation as part of its family of virtualization products. Oracle VM VirtualBox is installed on an existing host operating system as an application; this host application allows additional guest operating systems, each known as a Guest OS, to be loaded and run, each with its own virtual environment.
Supported host operating systems include Linux, Mac OS X, Windows XP, Windows Vista, Windows 7, Windows 8, Solaris, and OpenSolaris; there is also a port to FreeBSD. Supported guest operating systems include versions and derivations of Windows, Linux, BSD, OS/2, Solaris and others. Since release 3.2.0, VirtualBox also allows limited virtualization of Mac OS X guests on Apple hardware, though OSX86 can also be installed using VirtualBox.
Since version 4.1, Windows guests on supported hardware can take advantage of the recently implemented WDDM driver included in the guest additions; this allows Windows Aero to be enabled along with Direct3D support.
Innotek initially offered the application under a proprietary software license, making one version of the product available at no cost for personal or evaluation use, subject to the VirtualBox Personal Use and Evaluation License (PUEL). In January 2007, VirtualBox Open Source Edition (OSE) was released as free software, subject to the requirements of the GNU General Public License (GPL), version 2.
The original developer, innotek, also contributed to the development of OS/2 and Linux support in virtualization and OS/2 ports of products from Connectix which were later acquired by Microsoft. Specifically, innotek developed the “additions” code in both Microsoft Virtual PC and Microsoft Virtual Server, which enables various host-guest OS interactions like shared clipboards or dynamic viewport resizing.
Version summary 
Versions of VirtualBox include:
- version 1.3.2, released 2007, January (first public release, before that it was all internal)
- version 1.5.0, released 2007, September 4
- version 2.0.0, released 2008, September 4
- version 3.0.0, released 2009, June 30
- version 4.0.0, released 2010, December 22
- version 4.1.0, released 2011, July 19
- version 4.2.0, released 2012, September 13
With version 4 of Virtualbox, released in Dec. 2010, the core package is free software released under GNU General Public License version 2 (GPLv2). This is the fully featured package, excluding some proprietary components not available under GPLv2. These components provide support for USB 2.0 devices, RDP and PXE boot for Intel cards and are released as a separate "VirtualBox Oracle VM VirtualBox extension pack" under a proprietary Personal Use and Evaluation License (PUEL), which permits use of the software for personal use, educational use, or evaluation, free of charge.
Prior to version 4, there were two different packages of the VirtualBox software. The full package was offered free under the PUEL, with licenses for other commercial deployment purchasable from Oracle. A second package called the VirtualBox Open Source Edition (OSE) was released under GPLv2. This removed the same proprietary components not available under GPLv2.
Although VirtualBox has experimental support for Mac OS X guests, the end user license agreement of Mac OS X does not permit the operating system to run on non-Apple hardware, enforced within the operating system by calls to the Apple System Management Controller (SMC) in all Apple machines, which verifies the authenticity of the hardware.
Emulated environment 
Users of VirtualBox can load multiple guest OSs under a single host operating-system (host OS). Each guest can be started, paused and stopped independently within its own virtual machine (VM). The user can independently configure each VM and run it under a choice of software-based virtualization or hardware assisted virtualization if the underlying host hardware supports this. The host OS and guest OSs and applications can communicate with each other through a number of mechanisms including a common clipboard and a virtualized network facility (provided). Guest VMs can also directly communicate with each other if configured to do so.
Software-based virtualization 
In the absence of hardware-assisted virtualization, VirtualBox adopts a standard software-based virtualization approach. This mode supports 32-bit guest OSs which run in rings 0 and 3 of the Intel ring architecture.
- The system reconfigures the guest OS code, which would normally run in ring 0, to execute in ring 1 on the host hardware. Because this code contains many privileged instructions which cannot run natively in ring 1, VirtualBox employs a Code Scanning and Analysis Manager (CSAM) to scan the ring 0 code recursively before its first execution to identify problematic instructions and then calls the Patch Manager (PATM) to perform in-situ patching. This replaces the instruction with a jump to a VM-safe equivalent compiled code fragment in hypervisor memory.
- The guest user-mode code, running in ring 3, generally runs directly on the host hardware in ring 3.
In both cases, VirtualBox uses CSAM and PATM to inspect and patch the offending instructions whenever a fault occurs. VirtualBox also contains a dynamic recompiler, based on QEMU to recompile any real mode or protected mode code entirely (e.g. BIOS code, a DOS guest, or any operating system startup).
Hardware-assisted virtualization 
VirtualBox supports both Intel's VT-x and AMD's AMD-V hardware-virtualization. Making use of these facilities, VirtualBox can run each guest VM in its own separate address-space; the guest OS ring 0 code runs on the host at ring 0 in VMX non-root mode rather than in ring 1.
VirtualBox supports some guests (including 64-bit guests, SMP guests and certain proprietary OSs) only on hosts with hardware-assisted virtualization.
Device virtualization 
The system emulates hard disks in one of three disk image formats:
- a VirtualBox-specific container format, called "Virtual Disk Image" (VDI), storing files (with a .vdi suffix) on the host operating system
- VMware Virtual Machine Disk Format (VMDK)
- Microsoft Virtual PC VHD format
A VirtualBox virtual machine can, therefore, use disks previously created in VMware or Microsoft Virtual PC, as well as its own native format. VirtualBox can also connect to iSCSI targets and to raw partitions on the host, using either as virtual hard disks. VirtualBox emulates IDE (PIIX4 and ICH6 controllers), SCSI, SATA (ICH8M controller) and SAS controllers to which hard drives can be attached.
Both ISO images and host-connected physical devices can be mounted as CD/DVD drives. For example, the DVD image of a Linux distribution can be downloaded and used directly by VirtualBox.
By default VirtualBox provides graphics support through a custom virtual graphics-card that is VESA compatible. The Guest Additions for Windows, Linux, Solaris, OpenSolaris, or OS/2 guests include a special video-driver that increases video performance and includes additional features, such as automatically adjusting the guest resolution when resizing the VM window or desktop composition via virtualized WDDM drivers .
- AMD PCnet PCI II (Am79C970A)
- AMD PCnet-Fast III (Am79C973)
- Intel Pro/1000 MT Desktop (82540EM)
- Intel Pro/1000 MT Server (82545EM)
- Intel Pro/1000 T Server (82543GC)
The emulated network cards allow most guest OSs to run without the need to find and install drivers for networking hardware as they are shipped as part of the guest OS. A special paravirtualized network adapter is also available, which improves network performance by eliminating the need to match a specific hardware interface, but requires special driver support in the guest. (Many distributions of Linux ship with this driver included.) By default, VirtualBox uses NAT through which Internet software for end-users such as Firefox or ssh can operate. Bridged networking via a host network adapter or virtual networks between guests can also be configured. Up to 36 network adapters can be attached simultaneously, but only four are configurable through the graphical interface.
A USB 1.1 controller is emulated so that any USB devices attached to the host can be seen in the guest. The closed-source extension pack adds a USB 2.0 controller and, if VirtualBox acts as an RDP server, it can also use USB devices on the remote RDP client as if they were connected to the host, although only if the client supports this VirtualBox-specific extension (Oracle provides clients for Solaris, Linux and Sun Ray thin clients that can do this, and have promised support for other platforms in future versions).
Feature set 
||This section is in a list format that may be better presented using prose. (February 2012)|
||This section may be too technical for most readers to understand. (September 2012)|
- 64-bit guests (hardware virtualization only)
- NCQ support for SATA, SCSI and SAS raw disks and partitions
- Seamless mode
- Shared folders
- Special drivers and utilities to facilitate switching between systems
- Command line interaction (in addition to the GUI)
- Public API (Java, Python, SOAP, XPCOM) to control VM configuration and execution
- Nested paging for AMD-V and Intel VT (only for processors supporting SLAT and with SLAT enabled)
- Raw hard disk access – allows physical hard disk partitions on the host system to appear in the guest system
- VMware Virtual Machine Disk (VMDK) format support – allows VirtualBox to exchange disk images with VMware
- Microsoft VHD support
- 3D virtualization (Limited support for OpenGL was added to v2.1, more support was added to v2.2, OpenGL 2.0 and Direct3D support was added in VirtualBox 3.0)
- SMP support (up to 32 virtual CPUs per virtual machine), since version 3.0
- Teleportation (aka Live Migration), since version 3.1 (Broken since version 4.1)
- 2D video acceleration, since version 3.1
- Since version 3.2
- Mac OS X Server guest support – experimental
- Memory ballooning (not on Solaris hosts)
- RAM deduplication (Page Fusion) for Windows guests on 64-bit hosts
- CPU hot-plugging for Linux (hot-add and hot-remove) and certain Windows guests (hot-add only)
- Deleting snapshots while the VM is running
- Multi-monitor guest setups in the GUI, for Windows guests
- LSI Logic SAS controller emulation
- Remote Desktop Protocol (RDP) video acceleration
- Run and control guest applications from the host – for automated software deployments
- Since version 4.0
- The PUEL/OSE separation was given up in favor of an open source base product and a closed source extension pack that can be installed on top of the base product. As part of this change, additional components of VirtualBox were made open source (installers, documentation, device drivers)
- Intel HD audio emulation
- Intel ICH9 chipset emulation
- A new VM storage scheme where all VM data is stored in one single folder to improve VM portability
- Several UI enhancements including a new look with VM preview and scale mode
- On 32-bit hosts, VMs can each use more than 1.5 GB of RAM
- In addition to OVF, the single file OVA format is supported
- CPU use and I/O bandwidth can be limited per VM
- Support for Apple DMG images (DVD)
- Multi-monitor guest setups for Linux/Solaris guests (previously Windows only)
- Resizing of VDI and VHD images
- Since version 4.1
- Windows Aero support (experimental)
- Guest virtual machine cloning
The extension pack 
- Support for a virtual USB 2.0 controller (EHCI)
- VirtualBox RDP: support for proprietary remote connection protocol developed by Microsoft and Citrix.
- PXE boot for Intel cards
Virtual Disk Image 
VirtualBox uses its own format for storage containers – Virtual Disk Image (VDI). VirtualBox also supports other well-known storage formats such as VMDK (used in particular by VMware) as well as the VHD format used by Microsoft.
VirtualBox's command-line utility
VBoxManage includes options for cloning disks and importing and exporting file systems, however, it does not include a tool for increasing the size of the filesystem within a VDI container: this can be achieved in many ways with third-party tools (e.g. CloneVDI provides a GUI for cloning and increasing the size ) or in the guest OS itself.
See also 
- Comparison of platform virtual machines
- LHC@home, distributed computing project for particle physics at the Large Hadron Collider that uses VirtualBox
- Platform virtualization
- Virtual disk image
- VirtualBox downloads
- "VirtualBox – FreeBSD Wiki". Wiki.freebsd.org. 2009-06-16. Retrieved 2009-07-04.
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- "Editions". VirtualBox. Retrieved 2009-07-04.
- Interview with Andy Hall, Product Manager for Oracle VM VirtualBox
- "VirtualBox Manual, Section 10.4 Details about software virtualization". VirtualBox. Retrieved 2011-04-25.
- Dr. Oliver Diedrich (2007-01-15). "heise open – 15.01.07 – VirtualBox". Heise.de. Retrieved 2009-07-04.
- Jason Perlow (2010-05-21). "Virtualization Smackdown 2: Oracle VM VirtualBox 3.2 vs. VMware Workstation 7.1". ZDNET. Retrieved 2010-05-24.
- "Chapter 4. Guest Additions". VirtualBox. Retrieved 2011-01-17.
- "Chapter 6. Virtual networking". VirtualBox. Retrieved 2011-01-17.
- "Chapter 3. Configuring Virtual Machines". VirtualBox. Retrieved 2011-01-17.
- "VirtualBox 4.1.4 Manual – Chapter 7 Remote Virtual Machines". Oracle. 2011-10-03. Retrieved 2011-11-19.
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- "VirtualBox Bug #9455".
- Downloads – Oracle VM VirtualBox
- Guide/Virtual storage "Virtual storage". VirtualBox. 2009-10-30. Retrieved 2009-10-30.[dead link]
- "Howto increase hard disk size after installing a guest OS". End user forums for VirtualBox. 2009-10-30. Retrieved 2009-10-30.
- "VirtualBox changelog". Retrieved 2010-02-18.
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