source: vbox/trunk/doc/manual/en_US/user_Introduction.xml@ 32574

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<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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<chapter>
  <title id="Introduction">First steps</title>

  <para>Welcome to $VBOX_PRODUCT!</para>

  <para>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.</para>

  <para>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.</para>

  <para>The following screenshot shows you how VirtualBox, installed on a
  Linux machine, is running Windows 7 in a virtual machine window:</para>

  <para><mediaobject>
      <imageobject>
        <imagedata align="center" fileref="images/vm-vista-running.png"
                   width="10cm" />
      </imageobject>
    </mediaobject></para>

  <para>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.</para>

  <para>You can find a summary of VirtualBox's capabilities in <xref
  linkend="features-overview" />. For existing VirtualBox users who just want
  to see what's new in this release, there is a detailed list in <xref
  linkend="ChangeLog" />.</para>

  <sect1>
    <title>Why is virtualization useful?</title>

    <para>The techniques and features that VirtualBox provides are useful for
    several scenarios:</para>

    <itemizedlist>
      <listitem>
        <para><emphasis role="bold">Operating system support.</emphasis> 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.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Testing and disaster recovery.</emphasis>
        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.</para>

        <para>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.</para>

        <para>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.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Infrastructure consolidation.</emphasis>
        Virtualization can significantly reduce hardware and electricity
        costs. Servers today typically run with fairly low average 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.</para>

        <para>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.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Easier software installations.</emphasis>
        Virtual machines can be used by software vendors 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.</para>
      </listitem>
    </itemizedlist>
  </sect1>

  <sect1>
    <title id="virtintro">Some terminology</title>

    <para>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:</para>

    <glosslist>
      <glossentry>
        <glossterm>Host operating system (host OS):</glossterm>

        <glossdef>
          <para>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
          <xref linkend="hostossupport" />. 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.</para>
        </glossdef>
      </glossentry>

      <glossentry>
        <glossterm>Guest operating system (guest OS):</glossterm>

        <glossdef>
          <para>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
          <emphasis>may</emphasis> run as a guest, we officially support and
          optimize for a select few (which, however, include the most common
          ones).</para>

          <para>See <xref linkend="guestossupport" /> for details.</para>
        </glossdef>
      </glossentry>

      <glossentry>
        <glossterm>Virtual machine (VM).</glossterm>

        <glossdef>
          <para>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).</para>

          <para>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 CDs
          are mounted etc.) as well as state information (whether the VM is
          currently running, saved, its snapshots etc.).</para>

          <para>These settings are mirrored in the VirtualBox graphical user
          interface as well as the <computeroutput>VBoxManage</computeroutput>
          command line program; see <xref linkend="vboxmanage" />. In other
          words, a VM is also what you can see in its settings dialog.</para>
        </glossdef>
      </glossentry>

      <glossentry>
        <glossterm>Guest Additions.</glossterm>

        <glossdef>
          <para>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
          <emphasis>inside</emphasis> a VM to improve performance of the guest
          OS and to add extra features. This is described in detail in <xref
          linkend="guestadditions" />.</para>
        </glossdef>
      </glossentry>
    </glosslist>
  </sect1>

  <sect1 id="features-overview">
    <title>Features overview</title>

    <para>Here's a brief outline of VirtualBox's main features:</para>

    <itemizedlist>
      <listitem>
        <para><emphasis role="bold">Portability.</emphasis> VirtualBox runs on
        a large number of 32-bit and 64-bit host operating systems (again, see
        <xref linkend="hostossupport" /> for details).</para>

        <para>VirtualBox is a so-called "hosted" hypervisor (sometimes
        referred to as a "type 2" hypervisor). Whereas a "bare-metal" or "type
        1" hypervisor would run directly on the hardware, VirtualBox requires
        an existing operating system to be installed. It can thus run
        alongside existing applications on that host.</para>

        <para>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.</para>

        <para>In addition, virtual machines can easily be imported and
        exported using the Open Virtualization Format (OVF, see <xref
        linkend="ovf" />), an industry standard created for this purpose. You
        can even import OVFs that were created with a different virtualization
        software.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">No hardware virtualization
        required.</emphasis> 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 <xref
        linkend="hwvirt" />.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Guest Additions: shared folders, seamless
        windows, 3D virtualization.</emphasis> The VirtualBox Guest Additions
        are software packages which can be installed
        <emphasis>inside</emphasis> 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 <xref
        linkend="guestadditions" />.</para>

        <para>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 <xref
        linkend="sharedfolders" />.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Great hardware support.</emphasis> Among
        others, VirtualBox supports:</para>

        <itemizedlist>
          <listitem>
            <para><emphasis role="bold">Guest multiprocessing
            (SMP).</emphasis> VirtualBox can present up to 32 virtual CPUs to
            a virtual machine, irrespective of how many CPU cores are actually
            present in your host.</para>
          </listitem>

          <listitem>
            <para><emphasis role="bold">USB 2.0 device support.</emphasis>
            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
            <xref linkend="settings-usb" />.</para>
          </listitem>

          <listitem>
            <para><emphasis role="bold">Hardware compatibility.</emphasis>
            VirtualBox virtualizes a vast array of virtual devices, 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.</para>
          </listitem>

          <listitem>
            <para><emphasis role="bold">Full ACPI support.</emphasis> 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 <emphasis role="bold">ACPI power status support,</emphasis>
            VirtualBox can even report to ACPI-aware 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).</para>
          </listitem>

          <listitem>
            <para><emphasis role="bold">Multiscreen resolutions.</emphasis>
            VirtualBox virtual machines support screen resolutions many times
            that of a physical screen, allowing them to be spread over a large
            number of screens attached to the host system.</para>
          </listitem>

          <listitem>
            <para><emphasis role="bold">Built-in iSCSI support.</emphasis>
            This unique feature allows you to connect a virtual 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 <xref
            linkend="storage-iscsi" />.</para>
          </listitem>

          <listitem>
            <para><emphasis role="bold">PXE Network boot.</emphasis> The
            integrated virtual network cards of VirtualBox fully support
            remote booting via the Preboot Execution Environment (PXE).</para>
          </listitem>
        </itemizedlist>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Multigeneration branched
        snapshots.</emphasis> 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 <xref linkend="snapshots" />. You can delete
        snapshots while the virtual machine is running.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Clean architecture; unprecedented
        modularity.</emphasis> 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
        <xref linkend="frontends" /> for details.</para>

        <para>Due to its modular architecture, VirtualBox can also expose its
        full functionality and configurability through a comprehensive
        <emphasis role="bold">software development kit (SDK),</emphasis> which
        allows for integrating every aspect of VirtualBox with other software
        systems. Please see <xref linkend="VirtualBoxAPI" /> for
        details.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Remote machine display.</emphasis> 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.</para>

        <para>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.</para>

        <para>VRDP support is described in detail in <xref
        linkend="vrdp" />.</para>

        <para>On top of this special capacity, VirtualBox offers you more
        unique features:<itemizedlist>
            <listitem>
              <para><emphasis role="bold">Extensible RDP
              authentication.</emphasis> VirtualBox already supports Winlogon
              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
              <xref linkend="vrdp-authenticate-sdk" /> for details.</para>
            </listitem>

            <listitem>
              <para><emphasis role="bold">USB over RDP.</emphasis> 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 <xref
              linkend="usb-over-rdp" /> for details.</para>
            </listitem>
          </itemizedlist></para>
      </listitem>
    </itemizedlist>
  </sect1>

  <sect1>
    <title id="hostossupport">Supported host operating systems</title>

    <para>Currently, VirtualBox runs on the following host operating
    systems:</para>

    <itemizedlist>
      <listitem>
        <para><emphasis role="bold">Windows</emphasis> hosts:<itemizedlist>
            <listitem>
              <para>Windows XP, all service packs (32-bit)</para>
            </listitem>

            <listitem>
              <para>Windows Server 2003 (32-bit)</para>
            </listitem>

            <listitem>
              <para>Windows Vista (32-bit and 64-bit<footnote>
                  <para>Support for 64-bit Windows was added with VirtualBox
                  1.5.</para>
                </footnote>).</para>
            </listitem>

            <listitem>
              <para>Windows Server 2008 (32-bit and 64-bit)</para>
            </listitem>

            <listitem>
              <para>Windows 7 (32-bit and 64-bit)</para>
            </listitem>
          </itemizedlist></para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Mac OS X</emphasis> hosts:<footnote>
            <para>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.</para>
          </footnote></para>

        <itemizedlist>
          <listitem>
            <para>10.5 (Leopard, 32-bit)</para>
          </listitem>

          <listitem>
            <para>10.6 (Snow Leopard, 32-bit and 64-bit)</para>
          </listitem>
        </itemizedlist>

        <para>Intel hardware is required; please see <xref
        linkend="KnownIssues" /> also.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Linux</emphasis> hosts (32-bit and
        64-bit<footnote>
            <para>Support for 64-bit Linux was added with VirtualBox
            1.4.</para>
          </footnote>). Among others, this includes:<itemizedlist>
            <listitem>
              <para>Ubuntu 6.06 ("Dapper Drake"), 6.10 ("Edgy Eft"), 7.04
              ("Feisty Fawn"), 7.10 ("Gutsy Gibbon"), 8.04 ("Hardy Heron"),
              8.10 ("Intrepid Ibex"), 9.04 ("Jaunty Jackalope"), 9.10 ("Karmic
              Koala"), 10.04 ("Lucid Lynx").</para>
            </listitem>

            <listitem>
              <para>Debian GNU/Linux 3.1 ("sarge"), 4.0 ("etch") and 5.0
              ("lenny")</para>
            </listitem>

            <listitem>
              <para>Oracle Enterprise Linux 4 and 5</para>
            </listitem>

            <listitem>
              <para>Redhat Enterprise Linux 4 and 5</para>
            </listitem>

            <listitem>
              <para>Fedora Core 4 to 12</para>
            </listitem>

            <listitem>
              <para>Gentoo Linux</para>
            </listitem>

            <listitem>
              <para>SUSE Linux 9 and 10, openSUSE 10.3, 11.0, 11.1,
              11.2</para>
            </listitem>

            <listitem>
              <para>Mandriva 2007.1, 2008.0, 2009.1, 2010.0</para>
            </listitem>
          </itemizedlist></para>

        <para>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 <xref linkend="install-linux-host" />.</para>

        <para>Note that starting with VirtualBox 2.1, Linux 2.4-based host
        operating systems are no longer supported.</para>
      </listitem>

      <listitem>
        <para><emphasis role="bold">Solaris</emphasis> hosts (32-bit and
        64-bit<footnote>
            <para>Support for OpenSolaris was added with VirtualBox
            1.6.</para>
          </footnote>) are supported with the restrictions listed in <xref
        linkend="KnownIssues" />:<itemizedlist>
            <listitem>
              <para>OpenSolaris (2008.05 and higher, "Nevada" build 86 and
              higher)</para>
            </listitem>

            <listitem>
              <para>Solaris 10 (u5 and higher)</para>
            </listitem>
          </itemizedlist></para>
      </listitem>
    </itemizedlist>
  </sect1>

  <sect1>
    <title>Installing and starting VirtualBox</title>

    <para>VirtualBox comes in many different packages, and <emphasis
    role="bold">installation</emphasis> 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 <xref linkend="installation" /> for details
    about the various installation methods.</para>

    <para>After installation, you can start VirtualBox as
    follows:<itemizedlist>
        <listitem>
          <para>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.</para>
        </listitem>

        <listitem>
          <para>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.)</para>
        </listitem>

        <listitem>
          <para>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
          <computeroutput>VirtualBox</computeroutput> in a terminal.</para>
        </listitem>
      </itemizedlist></para>

    <para>When you start VirtualBox for the first time, a window like the
    following should come up:</para>

    <para><mediaobject>
        <imageobject>
          <imagedata align="center" fileref="images/virtualbox-main-empty.png"
                     width="10cm" />
        </imageobject>
      </mediaobject>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.</para>

    <para>To give you an idea what VirtualBox might look like later, after you
    have created many machines, here's another example:</para>

    <para><mediaobject>
        <imageobject>
          <imagedata align="center" fileref="images/virtualbox-main.png"
                     width="10cm" />
        </imageobject>
      </mediaobject></para>
  </sect1>

  <sect1 id="gui-createvm">
    <title>Creating your first virtual machine</title>

    <para>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):</para>

    <para><mediaobject>
        <imageobject>
          <imagedata align="center" fileref="images/create-vm-1.png"
                     width="10cm" />
        </imageobject>
      </mediaobject>On the following pages, the wizard will ask you for the
    bare minimum of information that is needed to create a VM, in
    particular:<orderedlist>
        <listitem>
          <para>A <emphasis role="bold">name</emphasis> for your VM, and the
          <emphasis role="bold">type of operating system</emphasis> (OS) you
          want to install.</para>

          <para>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".</para>

          <para>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 <xref linkend="intro-64bitguests" />). It is therefore
          recommended to always set it to the correct value.</para>
        </listitem>

        <listitem>
          <para>The <emphasis role="bold">amount of memory (RAM)</emphasis>
          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.</para>

          <para><note>
              <para>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.</para>
            </note></para>

          <para>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.</para>

          <para>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.</para>

          <para><note>
              <para>VirtualBox restricts the amount of guest RAM to 1500 MB on
              32-bit Windows hosts and to 2560 MB on 32-bit Linux and Solaris
              hosts due to address-space limitations. These restrictions do
              not apply to 64-bit hosts.</para>
            </note></para>

          <para>As with the other settings, you can change this setting later,
          after you have created the VM.</para>
        </listitem>

        <listitem>
          <para>Next, you must specify a <emphasis role="bold">virtual hard
          disk</emphasis> for your VM.</para>

          <para>There are many and potentially complicated ways in which
          VirtualBox can provide hard disk space to a VM (see <xref
          linkend="storage" /> 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.</para>

          <para>The wizard shows you the following window:</para>

          <para><mediaobject>
              <imageobject>
                <imagedata align="center" fileref="images/create-vm-2.png"
                           width="10cm" />
              </imageobject>
            </mediaobject></para>

          <para>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.</para>

          <para>In the wizard, you have the following options:</para>

          <para><itemizedlist>
              <listitem>
                <para>If you have previously created any virtual hard disks
                which have not been attached to other virtual machines, you
                can select those from the drop-down list in the wizard
                window.</para>
              </listitem>

              <listitem>
                <para>Otherwise, to create a new virtual hard disk, press the
                <emphasis role="bold">"New"</emphasis> button.</para>
              </listitem>

              <listitem>
                <para>Finally, for more complicated operations with virtual
                disks, the <emphasis role="bold">"Existing..."</emphasis>
                button will bring up the Virtual Media Manager, which is
                described in more detail in <xref linkend="vdis" />.</para>
              </listitem>
            </itemizedlist>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.</para>

          <para>This brings up another window, the <emphasis
          role="bold">"Create New Virtual Disk Wizard".</emphasis></para>

          <para>VirtualBox supports two types of image files:<itemizedlist>
              <listitem>
                <para>A <emphasis role="bold">dynamically expanding
                file</emphasis> will only grow in size when the guest actually
                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.</para>
              </listitem>

              <listitem>
                <para>A <emphasis role="bold">fixed-size file</emphasis> 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.</para>
              </listitem>
            </itemizedlist></para>

          <para>For details about the differences, please refer to <xref
          linkend="vdidetails" />.</para>

          <para>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:</para>

          <mediaobject>
            <imageobject>
              <imagedata align="center" fileref="images/create-vdi-1.png"
                         width="10cm" />
            </imageobject>
          </mediaobject>

          <para>After having selected or created your image file, again press
          <emphasis role="bold">"Next"</emphasis> to go to the next
          page.</para>
        </listitem>

        <listitem>
          <para>After clicking on <emphasis role="bold">"Finish"</emphasis>,
          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.</para>
        </listitem>
      </orderedlist></para>
  </sect1>

  <sect1>
    <title>Running your virtual machine</title>

    <para>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.</para>

    <para>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 <xref linkend="virtintro" />.</para>

    <para>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.</para>

    <para>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 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 or DVD handy, which VirtualBox can then present to the
    virtual machine.</para>

    <para>In both cases, after making the choices in the wizard, you will be
    able to install your operating system.</para>

    <para>In general, you can use the virtual machine much like you would use
    a real computer. There are couple of points worth mentioning
    however.</para>

    <sect2>
      <title>Keyboard and mouse support in virtual machines</title>

      <sect3>
        <title id="keyb_mouse_normal">Capturing and releasing keyboard and
        mouse</title>

        <para>As of version 3.2, VirtualBox provides a virtual USB tablet
        device to new virtual machines through which mouse events are
        communicated to the guest operating system. As a result, if you are
        running a fairly recent guest operating system that can handle such
        devices, mouse support may work out of the box without the mouse being
        "captured" as described below; see <xref
        linkend="settings-motherboard" /> for more information.</para>

        <para>Otherwise, if the virtual machine only sees standard PS/2 mouse
        and keyboard devices, 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
        full-screen mode, your VM needs to share keyboard and mouse with other
        applications and possibly other VMs on your host.</para>

        <para>As a result, initially after installing a guest 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
        <emphasis>second</emphasis> mouse pointer which will always be
        confined to the limits of the VM window. Basically, you activate the
        VM by clicking inside it.</para>

        <para>To return ownership of keyboard and mouse to your host operating
        system, VirtualBox reserves a special key on your keyboard for itself:
        the <emphasis role="bold">"host key".</emphasis> By default, this is
        the <emphasis>right Control key</emphasis> 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 <emphasis>at the
        bottom right of your VM window,</emphasis> should you have forgotten
        about it:</para>

        <para><mediaobject>
            <imageobject>
              <imagedata align="center" fileref="images/vm-hostkey.png"
                         width="7cm" />
            </imageobject>
          </mediaobject>In detail, all this translates into the
        following:</para>

        <para><itemizedlist>
            <listitem>
              <para>Your <emphasis role="bold">keyboard</emphasis> 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.</para>

              <para>To release keyboard ownership, press the Host key (as
              explained above, typically the right Control key).</para>

              <para>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.</para>
            </listitem>

            <listitem>
              <para>Your <emphasis role="bold">mouse</emphasis> 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.</para>

              <para>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.</para>

              <para>To release ownership of your mouse by the VM, also press
              the Host key.</para>
            </listitem>
          </itemizedlist></para>

        <para>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.</para>

        <para>This will be described later in <xref
        linkend="guestadditions" />.</para>
      </sect3>

      <sect3>
        <title>Typing special characters</title>

        <para>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 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.</para>

        <itemizedlist>
          <listitem>
            <para>Host operating systems reserve certain key combinations for
            themselves. For example, it is impossible to enter the <emphasis
            role="bold">Ctrl+Alt+Delete</emphasis> 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
            <emphasis>host</emphasis>.</para>

            <para>Also, on Linux and Solairs hosts, which use the X Window
            System, the key combination <emphasis
            role="bold">Ctrl+Alt+Backspace</emphasis> 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 <emphasis>host</emphasis> graphical
            user interface (and kill all running programs, including
            VirtualBox, in the process).</para>

            <para>Third, on Linux hosts supporting virtual terminals, the key
            combination <emphasis role="bold">Ctrl+Alt+Fx</emphasis> (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
            <emphasis>host</emphasis>.</para>

            <para>If, instead, you want to send these key combinations to the
            <emphasis>guest</emphasis> operating system in the virtual
            machine, you will need to use one of the following methods:</para>

            <itemizedlist>
              <listitem>
                <para>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.</para>
              </listitem>

              <listitem>
                <para>Press special key combinations with the Host key
                (normally the right Control key), which VirtualBox will then
                translate for the virtual machine:<itemizedlist>
                    <listitem>
                      <para><emphasis role="bold">Host key + Del</emphasis> to
                      send Ctrl+Alt+Del (to reboot the guest);</para>
                    </listitem>

                    <listitem>
                      <para><emphasis role="bold">Host key +
                      Backspace</emphasis> to send Ctrl+Alt+Backspace (to
                      restart the graphical user interface of a Linux or
                      Solaris guest);</para>
                    </listitem>

                    <listitem>
                      <para><emphasis role="bold">Host key + F1</emphasis> (or
                      other function keys) to simulate Ctrl+Alt+F1 (or other
                      function keys, i.e. to switch between virtual terminals
                      in a Linux guest).</para>
                    </listitem>
                  </itemizedlist></para>
              </listitem>
            </itemizedlist>
          </listitem>

          <listitem>
            <para>For some other keyboard combinations such as <emphasis
            role="bold">Alt-Tab</emphasis> (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" -&gt; "Preferences" -&gt; "Input" -&gt;
            "Auto-capture keyboard".</para>
          </listitem>
        </itemizedlist>
      </sect3>
    </sect2>

    <sect2>
      <title>Changing removable media</title>

      <para>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.</para>

      <para>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.</para>

      <para>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 <xref
      linkend="configbasics" />.</para>
    </sect2>

    <sect2>
      <title>Saving the state of the machine</title>

      <para>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.</para>

      <para><mediaobject>
          <imageobject>
            <imagedata align="center" fileref="images/vm-close.png"
                       width="7cm" />
          </imageobject>
        </mediaobject>The difference between these three options is crucial.
      They mean:</para>

      <itemizedlist>
        <listitem>
          <para><emphasis role="bold">Save the machine state:</emphasis> With
          this option, VirtualBox "freezes" the virtual machine 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.</para>

          <para>Saving the state of a virtual machine is thus in some ways
          similar to suspending a laptop computer (e.g. by closing its
          lid).</para>
        </listitem>

        <listitem>
          <para><emphasis role="bold">Send the shutdown signal.</emphasis>
          This will send an ACPI shutdown signal to the virtual 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.</para>
        </listitem>

        <listitem>
          <para><emphasis role="bold">Power off the machine:</emphasis> With
          this option, VirtualBox also stops running the virtual machine, but
          <emphasis>without</emphasis> saving its state.</para>

          <para>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.</para>

          <para>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.</para>

          <para>As an exception, if your virtual machine has any snapshots
          (see the next chapter), you can use this option to quickly <emphasis
          role="bold">restore the current snapshot</emphasis> of the virtual
          machine. Only in that case, powering off the machine is not
          harmful.</para>
        </listitem>
      </itemizedlist>

      <para>The <emphasis role="bold">"Discard"</emphasis> 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.</para>
    </sect2>
  </sect1>

  <sect1 id="snapshots">
    <title>Snapshots</title>

    <para>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.</para>

    <para>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.</para>

    <para>There are three operations related to snapshots:<orderedlist>
        <listitem>
          <para>You can <emphasis role="bold">take a
          snapshot</emphasis>.<itemizedlist>
              <listitem>
                <para>If your VM is currently running, select "Take snapshot"
                from the "Machine" pull-down menu of the VM window.</para>
              </listitem>

              <listitem>
                <para>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<itemizedlist>
                    <listitem>
                      <para>either on the small camera icon (for "Take
                      snapshot") or</para>
                    </listitem>

                    <listitem>
                      <para>right-click on the "Current State" item in the
                      list and select "Take snapshot" from the menu.</para>
                    </listitem>
                  </itemizedlist></para>
              </listitem>
            </itemizedlist></para>

          <para>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.</para>

          <para>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 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:<mediaobject>
              <imageobject>
                <imagedata align="center" fileref="images/snapshots-1.png"
                           width="10cm" />
              </imageobject>
            </mediaobject></para>

          <para>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.</para>
        </listitem>

        <listitem>
          <para>You can <emphasis role="bold">restore a snapshot</emphasis> 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.<footnote>
              <para>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 <emphasis>any</emphasis> snapshot, going backward and
              forward in time.</para>
            </footnote></para>

          <note>
            <para>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 <emphasis>will be lost. </emphasis>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 <computeroutput>VBoxManage</computeroutput> interface
            and use it to store your data. As write-through hard drives are
            <emphasis>not</emphasis> included in snapshots, they remain
            unaltered when a machine is reverted. See <xref
            linkend="hdimagewrites" os="" /> for details.</para>
          </note>

          <para>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.</para>
        </listitem>

        <listitem>
          <para>You can also <emphasis role="bold">delete a
          snapshot</emphasis>, 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. To delete a
          snapshot, right-click on it in the snapshots tree and select
          "Delete". As of VirtualBox 3.2, snapshots can be deleted even while
          a machine is running.<note>
              <para>Whereas taking and restoring snapshots are fairly quick
              operations, deleting a snapshot can take a considerable amount
              of time since large amounts of data may need to be copied
              between several disk image files. Temporary disk files may also
              need large amounts of disk space while the operation is in
              progress.</para>
            </note></para>

          <para>There are some situations which cannot be handled while a VM
          is running, and you will get an appropriate message that you need to
          perform this snapshot deletion when the VM is shut down.</para>
        </listitem>
      </orderedlist></para>

    <para>Think of a snapshot as a point in time that you have preserved. More
    formally, a snapshot consists of three things:<itemizedlist>
        <listitem>
          <para>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.)</para>
        </listitem>

        <listitem>
          <para>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.</para>

          <para>(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 <xref
          linkend="hdimagewrites" />. 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 <xref
          linkend="diffimages" />.)</para>
        </listitem>

        <listitem>
          <para>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.</para>
        </listitem>
      </itemizedlist></para>
  </sect1>

  <sect1>
    <title id="configbasics">Virtual machine configuration</title>

    <para>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.</para>

    <para>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.</para>

    <note>
      <para>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.</para>
    </note>

    <para>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 <xref
    linkend="BasicConcepts" />. Even more parameters are available with the
    command line interface; see <xref linkend="vboxmanage" />.</para>

    <para>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 CD or a DVD available the first time you start it, in
    order to install your guest operating system.</para>

    <para>For this, you have two options:</para>

    <itemizedlist>
      <listitem>
        <para>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.</para>

        <para>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).</para>

        <para>This will allow your VM to access the media in your host drive,
        and you can proceed to install from there.</para>
      </listitem>

      <listitem>
        <para>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.</para>

        <para>In this case, in the settings dialog, go to the "CD/DVD-ROM"
        section and select "ISO image file". This brings up the Virtual Media
        Manager, where you perform the following steps:</para>

        <para><orderedlist>
            <listitem>
              <para>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.</para>
            </listitem>

            <listitem>
              <para>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.</para>
            </listitem>
          </orderedlist></para>

        <para>The Virtual Media Manager is described in detail in <xref
        linkend="vdis" />.</para>
      </listitem>
    </itemizedlist>
  </sect1>

  <sect1>
    <title>Deleting virtual machines</title>

    <para>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.</para>

    <para>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.</para>

    <para>However, any hard disk images attached to the machine will be kept;
    you can delete those separately using the Virtual Media Manager; see <xref
    linkend="vdis" />.</para>

    <para>You cannot delete a machine which has snapshots or is in a saved
    state, so you must discard these first.</para>
  </sect1>

  <sect1 id="ovf">
    <title>Importing and exporting virtual machines</title>

    <para>Starting with version 2.2, VirtualBox can import and export virtual
    machines in the industry-standard Open Virtualization Format (OVF).</para>

    <para>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 <emphasis role="bold">virtual
    appliances</emphasis>: 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>
        <para>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 <xref
        linkend="KnownIssues" />.</para>
      </note></para>

    <para>An appliance in OVF format will typically consist of several
    files:<orderedlist>
        <listitem>
          <para>one or several disk images, typically in the widely-used VMDK
          format (see <xref linkend="vdidetails" />) and</para>
        </listitem>

        <listitem>
          <para>a textual description file in an XML dialect with an
          <computeroutput>.ovf</computeroutput> extension.</para>
        </listitem>
      </orderedlist></para>

    <para>These files must reside in the same directory for VirtualBox to be
    able to import them.</para>

    <para>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.</para>

    <para>To <emphasis role="bold">import</emphasis> an appliance in OVF
    format, select "File" -&gt; "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
    <computeroutput>.ovf</computeroutput> file extension.</para>

    <para>If VirtualBox can handle the file, a dialog similar to the following
    will appear:</para>

    <para><mediaobject>
        <imageobject>
          <imagedata align="center" fileref="images/ovf-import.png"
                     width="10cm" />
        </imageobject>
      </mediaobject>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 <emphasis
    role="bold">"Import"</emphasis>, 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.</para>

    <para>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.</para>

    <para>For how to import an image at the command line, please see <xref
    linkend="vboxmanage-import" />.</para>

    <para>Conversely, to <emphasis role="bold">export</emphasis> virtual
    machines that you already have in VirtualBox, select the machines and
    "File" -&gt; "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.</para>

    <para>For how to export an image at the command line, please see <xref
    linkend="vboxmanage-export" />.<note>
        <para>OVF cannot describe snapshots that were taken for a virtual
        machine. As a result, when you export a virtual machine that has
        snapshots, only the current state of the machine will be exported, and
        the disk images in the export will have a "flattened" state identical
        to the current state of the virtual machine.</para>
      </note></para>
  </sect1>

  <sect1 id="frontends">
    <title>Alternative front-ends</title>

    <para>As briefly mentioned in <xref linkend="features-overview" />,
    VirtualBox has a very flexible internal design that allows you to use
    different front-ends to control the same virtual machines. To illustrate,
    you can, for example, start a virtual machine with VirtualBox's
    easy-to-use graphical user interface and then stop it from the command
    line. With VirtualBox's support for the Remote Desktop Protocol (VRDP),
    you can even run virtual machines remotely on a headless server and have
    all the graphical output redirected over the network.</para>

    <para>In detail, the following front-ends are shipped in the standard
    VirtualBox package:</para>

    <para><orderedlist>
        <listitem>
          <para><computeroutput>VirtualBox</computeroutput> is our graphical
          user interface (GUI), which most of this User Manual is dedicated to
          describing, especially in <xref linkend="BasicConcepts" />. While
          this is the easiest-to-use of our interfaces, it does not (yet)
          cover all the features that VirtualBox provides. Still, this is the
          best way to get to know VirtualBox initially.</para>
        </listitem>

        <listitem>
          <para><computeroutput>VBoxManage</computeroutput> is our
          command-line interface for automated and very detailed control of
          every aspect of VirtualBox. It is described in <xref
          linkend="vboxmanage" />.</para>
        </listitem>

        <listitem>
          <para><computeroutput>VBoxSDL</computeroutput> is an alternative,
          simple graphical front-end with an intentionally limited feature
          set, designed to only display virtual machines that are controlled
          in detail with <computeroutput>VBoxManage</computeroutput>. This is
          interesting for business environments where displaying all the bells
          and whistles of the full GUI is not feasible.
          <computeroutput>VBoxSDL</computeroutput> is described in <xref
          linkend="vboxsdl" />.</para>
        </listitem>

        <listitem>
          <para>Finally, <computeroutput>VBoxHeadless</computeroutput> is yet
          another front-end that produces no visible output on the host at
          all, but merely acts as a VRDP server. Now, even though the other
          graphical front-ends (VirtualBox and VBoxSDL) also have VRDP support
          built-in and can act as a VRDP server, this particular front-end
          requires no graphics support. This is useful, for example, if you
          want to host your virtual machines on a headless Linux server that
          has no X Window system installed. For details, see <xref
          linkend="vboxheadless" />.</para>
        </listitem>
      </orderedlist>If the above front-ends still do not satisfy your
    particular needs, it is relatively painless to create yet another
    front-end to the complex virtualization engine that is the core of
    VirtualBox, as the VirtualBox core neatly exposes all of its features in a
    clean API; please refer to <xref linkend="VirtualBoxAPI" />.</para>
  </sect1>
</chapter>