VirtualBox is a cross-platform virtualization application. What does that mean? For
one thing, 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 following screenshot shows you how VirtualBox, installed on a Linux machine,
is running Windows 7 in a virtual machine window:
In this User Manual, we’ll begin simply with a quick introduction to virtualization
and how to get your first virtual machine running with the easy-to-use VirtualBox
graphical user interface. Subsequent chapters will go into much more detail covering
more powerful tools and features, but fortunately, it is not necessary to read the entire
User Manual before you can use VirtualBox.
9
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 forward 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.
10
1 First steps
1.2 Some terminology
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): 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; for details, please see chapter 1.4,
Supported host operating systems, page 14. While the various VirtualBox versions
are usually discussed together in this document, there may be platform-specific
differences which we will point out where appropriate.
Guest operating system (guest OS): 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).
See chapter 3.1, Supported guest operating systems, page 44 for details.
Virtual machine (VM). When running, a VM is the special environment that
VirtualBox creates for your guest operating system. So, 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 by use of the VirtualBox Remote Desktop Protocol (VRDP).
Sometimes we also use the term “virtual machine” 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
CD-ROMs 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 graphical user interface as well as
the VBoxManage command line program; see chapter 8, VBoxManage reference,
page 106. In other words, a VM is also what you can see in its settings dialog.
Guest Additions. With “Guest Additions”, we refer to special software packages that
are shipped with VirtualBox. Even though they are part of VirtualBox, they are
designed to be installed inside a VM to improve performance of the guest OS and
to add extra features. This is described in detail in chapter 4, Guest Additions,
page 60.
11
1 First steps
1.3 Features overview
Here’s a brief outline of VirtualBox’s main features:
• Portability. VirtualBox runs on a large number of 32-bit and 64-bit host oper-
ating systems (again, see chapter 1.4, Supported host operating systems, page 14
for details).
To a very large degree, VirtualBox is functionally identical on all of the host
platforms, and the same file and image formats are used. This allows you to
run virtual machines created on one host on another host with a different host
operating system; for example, you can create a virtual machine on Windows
and then run it under Linux.
In addition, virtual machines can easily be imported and exported using the
Open Virtualization Format (OVF, see chapter 1.11, Importing and exporting vir-
tual machines, page 29), an industry standard created for this purpose. You can
even import OVFs that were created with a different virtualization software.
• No hardware virtualization required. For many scenarios, VirtualBox does
not require the processor features built into newer hardware like Intel VT-x or
AMD-V. As opposed to many other virtualization solutions, you can therefore use
VirtualBox even on older hardware where these features are not present. More
details can be found in chapter 3.4.3, “Acceleration” tab: hardware vs. software
virtualization, page 49.
• Guest Additions: shared folders, seamless windows, 3D virtualization. The
VirtualBox Guest Additions are software packages which can be installed inside
of supported guest systems to improve their performance and to provide additional integration and communication with the host system. After installing the
Guest Additions, a virtual machine will support automatic adjustment of video
resolutions, seamless windows, accelerated 3D graphics and more. The Guest
Additions are described in detail in chapter 4, Guest Additions, page 60.
In particular, Guest Additions provide for “shared folders”, which let you access
files from the host system from within a guest machine. Shared folders are
described in chapter 4.7, Folder sharing, page 68.
• Great hardware support. Among others, VirtualBox supports:
– Guest multiprocessing (SMP). VirtualBox can present up to 32 virtual
CPUs to a virtual machine, irrespective of how many CPU cores are actually
present in your host.
– USB 2.0 device support. VirtualBox implements a virtual USB controller
and allows you to connect arbitrary USB devices to your virtual machines
without having to install device-specific drivers on the host. USB support
is not limited to certain device categories. For details, see chapter 3.10.1,
USB settings, page 56.
12
1 First steps
– Hardware compatibility. VirtualBox virtualizes a vast array of virtual de-
vices, among them many devices that are typically provided by other virtualization platforms. That includes IDE, SCSI and SATA hard disk controllers,
several virtual network cards and sound cards, virtual serial and parallel
ports and an Input/Output Advanced Programmable Interrupt Controller
(I/O APIC), which is found in many modern PC systems. This eases cloning
of PC images from real machines and importing of third-party virtual machines into VirtualBox.
– Full ACPI support.The Advanced Configuration and Power Interface
(ACPI) is fully supported by VirtualBox. This eases cloning of PC images
from real machines or third-party virtual machines into VirtualBox. With its
unique ACPI power status support, VirtualBox can even report to ACPIaware guest operating systems the power status of the host. For mobile
systems running on battery, the guest can thus enable energy saving and
notify the user of the remaining power (e.g. in fullscreen modes).
– Multiscreen resolutions. VirtualBox virtual machines support screen res-
olutions many times that of a physical screen, allowing them to be spread
over a large number of screens attached to the host system.
– Built-in iSCSI support. This unique feature allows you to connect a vir-
tual machine directly to an iSCSI storage server without going through the
host system. The VM accesses the iSCSI target directly without the extra
overhead that is required for virtualizing hard disks in container files. For
details, see chapter 5.8, iSCSI servers, page 86.
– PXE Network boot. The integrated virtual network cards of VirtualBox
fully support remote booting via the Preboot Execution Environment (PXE).
• Multigeneration branched snapshots. VirtualBox can save arbitrary snapshots
of the state of the virtual machine. You can go back in time and revert the virtual
machine to any such snapshot and start an alternative VM configuration from
there, effectively creating a whole snapshot tree. For details, see chapter 1.8,
Snapshots, page 25.
• Clean architecture; unprecedented modularity. VirtualBox has an extremely
modular design with well-defined internal programming interfaces and a clean
separation of client and server code. This makes it easy to control it from several
interfaces at once: for example, you can start a VM simply by clicking on a
button in the VirtualBox graphical user interface and then control that machine
from the command line, or even remotely. See chapter 7, Alternative front-ends;
remote virtual machines, page 96 for details.
Due to its modular architecture, VirtualBox can also expose its full functionality
and configurability through a comprehensive software development kit (SDK),
which allows for integrating every aspect of VirtualBox with other software systems. Please see chapter 10, VirtualBox programming interfaces, page 154 for
details.
13
1 First steps
• Remote machine display.You can run any virtual machine in a special
VirtualBox program that acts as a server for the VirtualBox Remote Desktop Protocol (VRDP), a backward-compatible extension of the standard Remote Desktop Protocol. With this unique feature, VirtualBox provides high-performance
remote access to any virtual machine.
VirtualBox’s VRDP support does not rely on the RDP server that is built into
Microsoft Windows. Instead, a custom VRDP server has been built directly into
the virtualization layer. As a result, it works with any operating system (even
in text mode) and does not require application support in the virtual machine
either.
VRDP support is described in detail in chapter 7.4, Remote virtual machines
(VRDP support), page 99.
On top of this special capacity, VirtualBox offers you more unique features:
on Windows and PAM on Linux for RDP authentication. In addition, it
includes an easy-to-use SDK which allows you to create arbitrary interfaces
for other methods of authentication; see chapter 9.4, Custom external VRDP
authentication, page 139 for details.
– USB over RDP. Via RDP virtual channel support, VirtualBox also allows
you to connect arbitrary USB devices locally to a virtual machine which is
running remotely on a VirtualBox RDP server; see chapter 7.4.4, Remote
USB, page 103 for details.
1.4 Supported host operating systems
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-bit1).
– Windows Server 2008 (32-bit and 64-bit)
– Windows 7 (32-bit and 64-bit)
• Mac OS X hosts:
– 10.5 (Leopard, 32-bit)
1
Support for 64-bit Windows was added with VirtualBox 1.5.
2
Preliminary Mac OS X support (beta stage) was added with VirtualBox 1.4, full support with 1.6. Mac OS
X 10.4 (Tiger) support was removed with VirtualBox 3.1.
2
14
1 First steps
– 10.6 (Snow Leopard, 32-bit and 64-bit)
Intel hardware is required; please see chapter 13, Known limitations, page 237
also.
• Linux hosts (32-bit and 64-bit3). Among others, this includes:
– Debian GNU/Linux 3.1 (“sarge”), 4.0 (“etch”) and 5.0 (“lenny”)
– Fedora Core 4 to 11
– Gentoo Linux
– Redhat Enterprise Linux 4 and 5
– SUSE Linux 9 and 10, openSUSE 10.3, 11.0 and 11.1
It should be possible to use VirtualBox on most systems based on Linux kernel
2.6 using either the VirtualBox installer or by doing a manual installation; see
chapter 2.3, Installing on Linux hosts, page 34.
Note that starting with VirtualBox 2.1, Linux 2.4-based host operating systems
are no longer supported.
• Solaris hosts (32-bit and 64-bit4) are supported with the restrictions listed in
chapter 13, Known limitations, page 237:
– OpenSolaris (2008.05 and higher, “Nevada” build 86 and higher)
– Solaris 10 (u5 and higher)
1.5 Installing and starting VirtualBox
VirtualBox comes in many different packages, and installation depends on your host
platform. If you have installed software before, installation should be straightforward
as on each host platform, VirtualBox uses the installation method that is most common
and easy to use. If you run into trouble or have special requirements, please refer
to chapter 2, Installation details, page 32 for details about the various installation
methods.
After installation, you can start VirtualBox as follows:
• On a Windows host, in the standard “Programs” menu, click on the item in the
“VirtualBox” group. On Vista or Windows 7, you can also type “VirtualBox” in
the search box of the “Start” menu.
3
Support for 64-bit Linux was added with VirtualBox 1.4.
4
Support for OpenSolaris was added with VirtualBox 1.6.
15
1 First steps
• On a Mac OS X host, in the Finder, double-click on the “VirtualBox” item in the
“Applications” folder. (You may want to drag this item onto your Dock.)
• On a Linux or Solaris host, depending on your desktop environment, a
“VirtualBox” item may have been placed in either the “System” or “System Tools”
group of your “Applications” menu. Alternatively, you can type VirtualBox in
a terminal.
When you start VirtualBox for the first time, a window like the following should
come up:
On the left, you can see a pane that will later list all your virtual machines. Since
you have not created any, the list is empty. A row of buttons above it allows you to
create new VMs and work on existing VMs, once you have some. The pane on the
right displays the properties of the virtual machine currently selected, if any. Again,
since you don’t have any machines yet, the pane displays a welcome message.
To give you an idea what VirtualBox might look like later, after you have created
many machines, here’s another example:
16
1 First steps
1.6 Creating your first virtual machine
Click on the “New” button at the top of the VirtualBox window. A wizard will pop up
to guide you through setting up a new virtual machine (VM):
17
1 First steps
On the following pages, the wizard will ask you for the bare minimum of information
that is needed to create a VM, in particular:
1. A name for your VM, and the type of operating system (OS) you want to install.
The name is what you will later see in the VirtualBox main window, and what
your settings will be stored under. It is purely informational, but once you have
created a few VMs, you will appreciate if you have given your VMs informative
names. “My VM” probably is therefore not as useful as “Windows XP SP2”.
For “Operating System Type”, select the operating system that you want to install
later. Depending on your selection, VirtualBox will enable or disable certain VM
settings that your guest operating system may require. This is particularly important for 64-bit guests (see chapter 3.2, 64-bit guests, page 45). It is therefore
recommended to always set it to the correct value.
2. The amount of memory (RAM) that the virtual machine should have for itself.
Every time a virtual machine is started, VirtualBox will allocate this much memory from your host machine and present it to the guest operating system, which
will report this size as the (virtual) computer’s installed RAM.
Note: Choose this setting carefully! The memory you give to the VM will
not be available to your host OS while the VM is running, so do not specify
more than you can spare. For example, if your host machine has 1 GB of
RAM and you enter 512 MB as the amount of RAM for a particular virtual
machine, while that VM is running, you will only have 512 MB left for all the
other software on your host. If you run two VMs at the same time, even more
memory will be allocated for the second VM (which may not even be able to
start if that memory is not available). On the other hand, you should specify
as much as your guest OS (and your applications) will require to run properly.
A Windows XP guest will require at least a few hundred MB RAM to run properly,
and Windows Vista will even refuse to install with less than 512 MB. Of course,
if you want to run graphics-intensive applications in your VM, you may require
even more RAM.
So, as a rule of thumb, if you have 1 GB of RAM or more in your host computer,
it is usually safe to allocate 512 MB to each VM. But, in any case, make sure you
always have at least 256 to 512 MB of RAM left on your host operating system.
Otherwise you may cause your host OS to excessively swap out memory to your
hard disk, effectively bringing your host system to a standstill.
As with the other settings, you can change this setting later, after you have created the VM.
3. Next, you must specify a virtual hard disk for your VM.
18
1 First steps
There are many and potentially complicated ways in which VirtualBox can provide hard disk space to a VM (see chapter 5, Virtual storage, page 76 for details),
but the most common way is to use a large image file on your “real” hard disk,
whose contents VirtualBox presents to your VM as if it were a complete hard
disk.
The wizard shows you the following window:
The wizard allows you to create an image file or use an existing one. Note also
that the disk images can be separated from a particular VM, so even if you delete
a VM, you can keep the image, or copy it to another host and create a new VM
for it there.
In the wizard, you have the following options:
• If you have previously created any virtual hard disks which have not been
attached to other virtual machines, you can select those from the dropdown list in the wizard window.
• Otherwise, to create a new virtual hard disk, press the “New” button.
• Finally, for more complicated operations with virtual disks, the “Existing...“
button will bring up the Virtual Disk Manager, which is described in more
detail in chapter 5.3, The Virtual Media Manager, page 80.
Most probably, if you are using VirtualBox for the first time, you will want to
create a new disk image. Hence, press the “New” button.
This brings up another window, the “Create New Virtual Disk Wizard”.
VirtualBox supports two types of image files:
19
1 First steps
• A dynamically expanding file will only grow in size when the guest actu-
ally stores data on its virtual hard disk. It will therefore initially be small
on the host hard drive and only later grow to the size specified as it is filled
with data.
• A fixed-size file will immediately occupy the file specified, even if only a
fraction of the virtual hard disk space is actually in use. While occupying
much more space, a fixed-size file incurs less overhead and is therefore
slightly faster than a dynamically expanding file.
For details about the differences, please refer to chapter 5.2, Disk image files
(VDI, VMDK, VHD, HDD), page 79.
To prevent your physical hard disk from running full, VirtualBox limits the size
of the image file. Still, it needs to be large enough to hold the contents of
your operating system and the applications you want to install – for a modern
Windows or Linux guest, you will probably need several gigabytes for any serious
use:
After having selected or created your image file, again press “Next” to go to the
next page.
4. After clicking on “Finish”, your new virtual machine will be created. You will
then see it in the list on the left side of the main window, with the name you
have entered.
20
1 First steps
1.7 Running your virtual machine
You will now see your new virtual machine in the list of virtual machines, at the left of
the VirtualBox main window. To start the virtual machine, simply double-click on it,
or select it and press the “Start” button at the top.
This opens up a new window, and the virtual machine which you selected will boot
up. Everything which would normally be seen on the virtual system’s monitor is shown
in the window, as can be seen with the image in chapter 1.2, Some terminology, page
11.
Since this is the first time you are running this VM, another wizard will show up
to help you select an installation medium. Since the VM is created empty, it would
otherwise behave just like a real computer with no operating system installed: it will
do nothing and display an error message that it cannot boot an operating system.
For this reason, the “First Start Wizard” helps you select an operating system
medium to install an operating system from. In most cases, this will either be a real
CD-ROM or DVD (VirtualBox can then configure the virtual machine to use your host’s
drive), or you might have an ISO image of a CD-ROM or DVD handy, which VirtualBox
can then present to the virtual machine.
In both cases, after making the choices in the wizard, you will be able to install your
operating system.
In general, you can use the virtual machine much like you would use a real computer. There are couple of points worth mentioning however.
1.7.1 Keyboard and mouse support in virtual machines
1.7.1.1 Capturing and releasing keyboard and mouse
Since the operating system in the virtual machine does not “know” that it is not running on a real computer, it expects to have exclusive control over your keyboard and
mouse. This is, however, not the case since, unless you are running the VM in fullscreen mode, your VM needs to share keyboard and mouse with other applications
and possibly other VMs on your host.
As a result, initially after installing a host operating system and before you install
the guest additions (we will explain this in a minute), only one of the two – your VM
or the rest of your computer – can “own” the keyboard and the mouse. You will see a
second mouse pointer which will always be confined to the limits of the VM window.
Basically, you activate the VM by clicking inside it.
To return ownership of keyboard and mouse to your host operating system,
VirtualBox reserves a special key on your keyboard for itself: the “host key”. By
default, this is the right Control key on your keyboard; on a Mac host, the default host
key is the left Command key. You can change this default in the VirtualBox Global
Settings. In any case, the current setting for the host key is always displayed at thebottom right of your VM window, should you have forgotten about it:
21
1 First steps
In detail, all this translates into the following:
• Your keyboard is owned by the VM if the VM window on your host desktop
has the keyboard focus (and then, if you have many windows open in your guest
operating system as well, the window that has the focus in your VM). This means
that if you want to type within your VM, click on the title bar of your VM window
first.
To release keyboard ownership, press the Host key (as explained above, typically
the right Control key).
Note that while the VM owns the keyboard, some key sequences (like Alt-Tab for
example) will no longer be seen by the host, but will go to the guest instead.
After you press the host key to re-enable the host keyboard, all key presses will
go through the host again, so that sequences like Alt-Tab will no longer reach the
guest.
• Your mouse is owned by the VM only after you have clicked in the VM window.
The host mouse pointer will disappear, and your mouse will drive the guest’s
pointer instead of your normal mouse pointer.
Note that mouse ownership is independent of that of the keyboard: even after
you have clicked on a titlebar to be able to type into the VM window, your mouse
is not necessarily owned by the VM yet.
To release ownership of your mouse by the VM, also press the Host key.
As this behavior can be inconvenient, VirtualBox provides a set of tools and device
drivers for guest systems called the “VirtualBox Guest Additions” which make VM keyboard and mouse operation a lot more seamless. Most importantly, the Additions will
get rid of the second “guest” mouse pointer and make your host mouse pointer work
directly in the guest.
This will be described later in chapter 4, Guest Additions, page 60.
1.7.1.2 Typing special characters
Operating systems expect certain key combinations to initiate certain procedures.
Some of these key combinations may be difficult to enter into a virtual machine, as
22
1 First steps
there are three candidates as to who receives keyboard input: the host operating system, VirtualBox, or the guest operating system. Who of these three receives keypresses
depends on a number of factors, including the key itself.
• Host operating systems reserve certain key combinations for themselves. For
example, it is impossible to enter the Ctrl+Alt+Delete combination if you want
to reboot the guest operating system in your virtual machine, because this key
combination is usually hard-wired into the host OS (both Windows and Linux
intercept this), and pressing this key combination will therefore reboot your host.
Also, on Linux and Solairs hosts, which use the X Window System, the key combination Ctrl+Alt+Backspace normally resets the X server (to restart the entire
graphical user interface in case it got stuck). As the X server intercepts this combination, pressing it will usually restart your host graphical user interface (and
kill all running programs, including VirtualBox, in the process).
Third, on Linux hosts supporting virtual terminals, the key combination
Ctrl+Alt+Fx (where Fx is one of the function keys from F1 to F12) normally
allows to switch between virtual terminals. As with Ctrl+Alt+Delete, these
combinations are intercepted by the host operating system and therefore always
switch terminals on the host.
If, instead, you want to send these key combinations to the guest operating system in the virtual machine, you will need to use one of the following methods:
– Use the items in the “Machine” menu of the virtual machine window. There
you will find “Insert Ctrl+Alt+Delete” and “Ctrl+Alt+Backspace”; the latter will only have an effect with Linux or Solaris guests, however.
– Press special key combinations with the Host key (normally the right Con-
trol key), which VirtualBox will then translate for the virtual machine:
∗ Host key + Del to send Ctrl+Alt+Del (to reboot the guest);
∗ Host key + Backspace to send Ctrl+Alt+Backspace (to restart the
graphical user interface of a Linux or Solaris guest);
∗ Host key + F1 (or other function keys) to simulate Ctrl+Alt+F1 (or
other function keys, i.e. to switch between virtual terminals in a Linux
guest).
• For some other keyboard combinations such as Alt-Tab (to switch between open
windows), VirtualBox allows you to configure whether these combinations will
affect the host or the guest, if a virtual machine currently has the focus. This
is a global setting for all virtual machines and can be found under “File” ->
“Preferences” -> “Input” -> “Auto-capture keyboard”.
1.7.2 Changing removable media
While a virtual machine is running, you can change removable media in the “Devices”
menu of the VM’s window. Here you can select in detail what VirtualBox presents to
your VM as a CD, DVD, or floppy.
23
1 First steps
The settings are the same as would be available for the VM in the “Settings” dialog
of the VirtualBox main window, but since that dialog is disabled while the VM is in the
“running” or “saved” state, this extra menu saves you from having to shut down and
restart the VM every time you want to change media.
Hence, in the “Devices” menu, VirtualBox allows you to attach the host drive to the
guest or select a floppy or DVD image using the Disk Image Manager, all as described
in chapter 1.9, Virtual machine configuration, page 27.
1.7.3 Saving the state of the machine
When you click on the “Close” button of your virtual machine window (at the top right
of the window, just like you would close any other window on your system) (or press
the Host key together with “Q”), VirtualBox asks you whether you want to “save” or
“power off” the VM.
The difference between these three options is crucial. They mean:
• Save the machine state: With this option, VirtualBox “freezes” the virtual ma-
chine by completely saving its state to your local disk. When you later resume the
VM (by again clicking the “Start” button in the VirtualBox main window), you
will find that the VM continues exactly where it was left off. All your programs
will still be open, and your computer resumes operation.
Saving the state of a virtual machine is thus in some ways similar to suspending
a laptop computer (e.g. by closing its lid).
• Send the shutdown signal. This will send an ACPI shutdown signal to the vir-
tual machine, which has the same effect as if you had pressed the power button
on a real computer. So long as a fairly modern operating system is installed and
running in the VM, this should trigger a proper shutdown mechanism in the VM.
• Power off the machine: With this option, VirtualBox also stops running the
virtual machine, but without saving its state.
24
1 First steps
This is equivalent to pulling the power plug on a real computer without shutting
it down properly. If you start the machine again after powering it off, your
operating system will have to reboot completely and may begin a lengthy check
of its (virtual) system disks.
As a result, this should not normally be done, since it can potentially cause data
loss or an inconsistent state of the guest system on disk.
As an exception, if your virtual machine has any snapshots (see the next chapter),
you can use this option to quickly restore the current snapshot of the virtual
machine. Only in that case, powering off the machine is not harmful.
The “Discard” button in the main VirtualBox window discards a virtual machine’s
saved state. This has the same effect as powering it off, and the same warnings apply.
1.8 Snapshots
With snapshots, you can save a particular state of a virtual machine for later use. At
any later time, you can revert to that state, even though you may have changed the
VM considerably since then.
You can see the snapshots of a virtual machine by first selecting a machine from
the list on the left of the VirtualBox main window and then selecting the “Snapshots”
tab on the right. Initially, until you take a snapshot of the machine, that list is empty
except for the “Current state” item, which represents the “Now” point in the lifetime
of the virtual machine.
There are three operations related to snapshots:
1. You can take a snapshot.
• If your VM is currently running, select “Take snapshot” from the “Machine”
pull-down menu of the VM window.
• If your VM is currently in either the “saved” or the “powered off ” state (as
displayed next to the VM in the VirtualBox main window), click on the
“Snapshots” tab on the top right of the main window, and then
– either on the small camera icon (for “Take snapshot”) or
– right-click on the “Current State” item in the list and select “Take snap-
shot” from the menu.
In any case, a window will pop up and ask you for a snapshot name. This
name is purely for reference purposes to help you remember the state of the
snapshot. For example, a useful name would be “Fresh installation from scratch,
no external drivers”. You can also add a longer text in the “Description” field if
you want.
Your new snapshot will then appear in the list of snapshots under the “Snapshots”
tab. Underneath, you will see an item called “Current state”, signifying that the
25
1 First steps
current state of your VM is a variation based on the snapshot you took earlier.
If you later take another snapshot, you will see that they will be displayed in
sequence, and each subsequent snapshot is a derivation of the earlier one:
VirtualBox allows you to take an unlimited number of snapshots – the only limitation is the size of your disks. Keep in mind that each snapshot stores the state
of the virtual machine and thus takes some disk space.
2. You can restore a snapshot by right-clicking on any snapshot you have taken in
the list of snapshots. By restoring a snapshot, you go back (or forward) in time:
the current state of the machine is lost, and the machine is restored to exactly
the same state as it was when then snapshot was taken.
5
Note: Restoring a snapshot will affect the virtual hard drives that are connected to your VM, as the entire state of the virtual hard drive will be reverted
as well. This means also that all files that have been created since the snapshot and all other file changes will be lost. In order to prevent such data loss
while still making use of the snapshot feature, it is possible to add a second
hard drive in “write-through” mode using the VBoxManage interface and use
it to store your data. As write-through hard drives are not included in snapshots, they remain unaltered when a machine is reverted. See chapter 5.4,
Special image write modes, page 81 for details.
5
Both the terminology and the functionality of restoring snapshots has changed with VirtualBox 3.1. Before
that version, it was only possible to go back to the very last snapshot taken – not earlier ones, and the
operation was called “Discard current state” instead of “Restore last snapshot”. The limitation has been
lifted with version 3.1. It is now possible to restore any snapshot, going backward and forward in time.
26
1 First steps
By restoring an earlier snapshot and taking more snapshots from there, it is even
possible to create a kind of alternate reality and to switch between these different
histories of the virtual machine. This can result in a whole tree of virtual machine
snapshots, as shown in the screenshot above.
3. You can also delete a snapshot, which will not affect the state of the virtual
machine, but only release the files on disk that VirtualBox used to store the
snapshot data, thus freeing disk space.
Think of a snapshot as a point in time that you have preserved. More formally, a
snapshot consists of three things:
• It contains a complete copy of the VM settings, so that when you restore a snapshot, the VM settings are restored as well. (For example, if you changed the hard
disk configuration, that change is undone when you restore the snapshot.)
• The state of all the virtual disks attached to the machine is preserved. Going
back to a snapshot means that all changes, bit by bit, that had been made to the
machine’s disks will be undone as well.
(Strictly speaking, this is only true for virtual hard disks in “normal” mode. As
mentioned above, you can configure disks to behave differently with snapshots;
see chapter 5.4, Special image write modes, page 81. Even more formally and
technically correct, it is not the virtual disk itself that is restored when a snapshot
is restored. Instead, when a snapshot is taken, VirtualBox creates differencing
images which contain only the changes since the snapshot were taken, and when
the snapshot is restored, VirtualBox throws away that differencing image, thus
going back to the previous state. This is both faster and uses less disk space. For
the details, which can be complex, please see chapter 5.5, Differencing images,
page 83.)
• Finally, if you took a snapshot while the machine was running, the memory state
of the machine is also saved in the snapshot (the same way the memory can be
saved when you close the VM window) so that when you restore the snapshot,
execution resumes at exactly the point when the snapshot was taken.
1.9 Virtual machine configuration
When you select a virtual machine from the list in the main VirtualBox window, you
will see a summary of that machine’s settings on the right of the window, under the
“Details” tab.
Clicking on the “Settings” button in the toolbar at the top of VirtualBox main window
brings up a detailed window where you can configure many of the properties of the
VM that is currently selected. But be careful: even though it is possible to change all
VM settings after installing a guest operating system, certain changes might prevent a
guest operating system from functioning correctly if done after installation.
27
1 First steps
Note: The “Settings” button is disabled while a VM is either in the “running”
or “saved” state. This is simply because the settings dialog allows you to
change fundamental characteristics of the virtual computer that is created for
your guest operating system, and this operating system may not take it well
when, for example, half of its memory is taken away from under its feet. As a
result, if the “Settings” button is disabled, shut down the current VM first.
VirtualBox provides a plethora of parameters that can be changed for a virtual machine. The various settings that can be changed in the “Settings” window are described
in detail in chapter 3, Configuring virtual machines, page 44. Even more parameters
are available with the command line interface; see chapter 8, VBoxManage reference,
page 106.
For now, if you have just created an empty VM, you will probably be most interested
in the settings presented by the “CD/DVD-ROM” section if you want to make a CDROM or a DVD-ROM available the first time you start it, in order to install your guest
operating system.
For this, you have two options:
• If you have actual CD or DVD media from which you want to install your guest
operating system (e.g. in the case of a Windows installation CD or DVD), put the
media into your host’s CD or DVD drive.
Then, in the settings dialog, go to the “CD/DVD-ROM” section and select “Host
drive” with the correct drive letter (or, in the case of a Linux host, device file).
This will allow your VM to access the media in your host drive, and you can
proceed to install from there.
• If you have downloaded installation media from the Internet in the form of an
ISO image file (most probably in the case of a Linux distribution), you would
normally burn this file to an empty CD or DVD and proceed as just described.
With VirtualBox however, you can skip this step and mount the ISO file directly.
VirtualBox will then present this file as a CD or DVD-ROM drive to the virtual
machine, much like it does with virtual hard disk images.
In this case, in the settings dialog, go to the “CD/DVD-ROM” section and select
“ISO image file”. This brings up the Virtual Disk Image Manager, where you
perform the following steps:
1. Press the “Add” button to add your ISO file to the list of registered images.
This will present an ordinary file dialog that allows you to find your ISO file
on your host machine.
2. Back to the manager window, select the ISO file that you just added and
press the “Select” button. This selects the ISO file for your VM.
The Virtual Disk Image Manager is described in detail in chapter 5.3, The Virtual
Media Manager, page 80.
28
1 First steps
1.10 Deleting virtual machines
To remove a virtual machine which you no longer need, right-click on it in the list of
virtual machines in the main window and select “Delete” from the context menu that
comes up. All settings for that machine will be lost.
The “Delete” menu item is disabled while a machine is in “Saved” state. To delete
such a machine, discard the saved state first by pressing on the “Discard” button.
However, any hard disk images attached to the machine will be kept; you can delete
those separately using the Virtual Disk Manager; see chapter 5.3, The Virtual Media
Manager, page 80.
You cannot delete a machine which has snapshots or is in a saved state, so you must
discard these first.
1.11 Importing and exporting virtual machines
Starting with version 2.2, VirtualBox can import and export virtual machines in the
industry-standard Open Virtualization Format (OVF).
OVF is a cross-platform standard supported by many virtualization products which
allows for creating ready-made virtual machines that can then be imported into a
virtualizer such as VirtualBox. As opposed to other virtualization products, VirtualBox
now supports OVF with an easy-to-use graphical user interface as well as using the
command line. This allows for packaging so-called virtual appliances: disk images
together with configuration settings that can be distributed easily. This way one can
offer complete ready-to-use software packages (operating systems with applications)
that need no configuration or installation except for importing into VirtualBox.
Note: The OVF standard is complex, and support in VirtualBox is an ongoing
process. In particular, no guarantee is made that VirtualBox supports all appliances created by other virtualization software. For a list of know limitations,
please see chapter 13, Known limitations, page 237.
An appliance in OVF format will typically consist of several files:
1. one or several disk images, typically in the widely-used VMDK format (see chapter 5.2, Disk image files (VDI, VMDK, VHD, HDD), page 79) and
2. a textual description file in an XML dialect with an .ovf extension.
These files must reside in the same directory for VirtualBox to be able to import
them.
A future version of VirtualBox will also support packages that include the OVF XML
file and the disk images packed together in a single archive.
To import an appliance in OVF format, select “File” -> “Import appliance” from the
main window of the VirtualBox graphical user interface. Then open the file dialog and
navigate to the OVF text file with the .ovf file extension.
29
1 First steps
If VirtualBox can handle the file, a dialog similar to the following will appear:
This presents the virtual machines described in the OVF file and allows you to change
the virtual machine settings by double-clicking on the description items. Once you
click on “Import”, VirtualBox will copy the disk images and create local virtual machines with the settings described in the dialog. These will then show up in the list of
virtual machines.
Note that since disk images tend to be big, and VMDK images that come with virtual
appliances are typically shipped in a special compressed format that is unsuitable for
being used by virtual machines directly, the images will need to be unpacked and
copied first, which can take a few minutes.
For how to import an image at the command line, please see chapter 8.6, VBoxMan-
age import, page 118.
Conversely, to export virtual machines that you already have in VirtualBox, select
the machines and “File” -> “Export appliance”. A different dialog window shows up
that allows you to combine several virtual machines into an OVF appliance. Then, you
select the target location where the OVF and VMDK files should be stored, and the
conversion process begins. This can again take a while.
For how to export an image at the command line, please see chapter 8.7, VBoxMan-
age export, page 120.
30
Loading...
+ 253 hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.