= Getting started with virtualization

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This page deals with using Fedora to host virtual guests. For
information the different virtualization technologies available in
Fedora, see the link:Tools/Virtualization[dedicated page].

[[using-virtualization-on-fedora]]
Using virtualization on Fedora
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fedora uses the libvirt family of tools as its virtualization solution.
By default libvirt on Fedora will use Qemu to run guest instances.

For information on other virtualization platforms, refer to
http://virt.kernelnewbies.org/TechComparison.

Qemu can emulate a host machine in software, or given a CPU with
hardware support (see below) can use http://www.linux-kvm.org[KVM] to
provide a fast full virtualization.

Other virtualization products and packages are available but are not
covered by this guide.

[[installing-and-configuring-fedora-for-virtualized-guests]]
Installing and configuring Fedora For virtualized guests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This section covers setting up libvirt on your system. After the
successful completion of this section you will be able to create
virtualized guest operating systems.

[[system-requirements]]
System requirements
^^^^^^^^^^^^^^^^^^^

The common system requirements for virtualization on Fedora are:

* At least 600MB of hard disk storage per guest. A minimal command-line
Fedora system requires 600MB of storage. Standard fedora desktop guests
require at least 3GB of space.
* At least 256MB of RAM per guest plus 256 for the base OS. At least
756MB is recommended for each guest of a modern operating system. A good
rule of thumb is to think about how much memory is required for the
operating system normally and allocate that much to the virtualized
guest.

KVM requires a CPU with virtualization extensions, found on most
consumer CPUs made in the past couple years. These extensions are called
Intel VT or AMD-V. To check whether you have proper CPU support, run the
command:

....
$ egrep '^flags.*(vmx|svm)' /proc/cpuinfo 
....

If NOTHING is printed, your system does not support the relevant
extensions. You can still use the QEMU/KVM, but the emulator will fall
back to software virtualization, which is FAR FAR slower.

[[installing-the-virtualization-packages]]
Installing the virtualization packages
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

When installing Fedora, the virtualization packages can be installed by
selecting *Virtualization* in the Base Group in the installer. (This may
http://docs.fedoraproject.org/en-US/Fedora/13/html/Installation_Guide/s1-pkgselection-x86.html[no
longer apply to your installation method] though).

For existing Fedora installations, QEMU, KVM, and other virtualization
tools can be installed by running the following command which installs
the virtualization group:

[[fedora-22-to-current]]
Fedora 22 to current:
~~~~~~~~~~~~~~~~~~~~~

For Fedora 21 or previous installations, replace "dnf" with "yum." Yum
is now a deprecated package manager and is replaced by DNF on
installations of Fedora 22 and onward.

....
su -c "dnf install @virtualization"
....

This will install below Mandatory and Default packages.

....
$ dnf groupinfo virtualization

Group: Virtualisation
 Group-Id: virtualization
 Description: These packages provide a virtualisation environment.
 Mandatory Packages:
   =virt-install
 Default Packages:
   =libvirt-daemon-config-network
   =libvirt-daemon-kvm
   =qemu-kvm
   =virt-manager
   =virt-viewer
 Optional Packages:
   guestfs-browser
   libguestfs-tools
   python-libguestfs
   virt-top
....

This will install Mandatory, Default and Optional Packages.

....
su -c "dnf group install with-optional virtualization"
....

To start the service:

....
su -c "systemctl start libvirtd"
....

To start the service on boot:

....
su -c "systemctl enable libvirtd"
....

Verify that the kvm kernel modules were properly loaded:

....
$ lsmod | grep kvm
kvm_amd                55563  0 
kvm                   419458  1 kvm_amd
....

If that command did not list kvm_intel or kvm_amd, KVM is not properly
configured. See
link:How_to_debug_Virtualization_problems#Ensuring_system_is_KVM_capable[
Ensuring system is KVM capable] for troubleshooting tips.

[[networking-support]]
Networking Support
^^^^^^^^^^^^^^^^^^

By default libvirt will create a private network for your guests on the
host machine. This private network will use a 192.168.x.x subnet and not
be reachable directly from the network the host machine is on, but
virtual guests can use the host machine as a gateway and can connect out
via it. If you need to provide services on your guests that are
reachable via other machines on your host network you can use iptables
DNAT rules to forward in specific ports, or you can setup a Bridged env.

See the http://wiki.libvirt.org/page/Networking[libvirt networking setup
page] for more information on how to setup a Bridged network.

[[creating-a-fedora-guest]]
Creating a Fedora guest
^^^^^^^^^^^^^^^^^^^^^^^

The installation of Fedora guests using anaconda is supported. The
installation can be started on the command line via the `virt-install`
program or in the GUI program `virt-manager`.

[[creating-a-guest-with-virt-install]]
Creating a guest with virt-install
++++++++++++++++++++++++++++++++++

`virt-install` is a command line based tool for creating virtualized
guests. Refer to
http://virt-tools.org/learning/install-with-command-line/ for
understanding how to use this tool. Execute `virt-install --help` for
command line help.

`virt-install` can use kickstart files, for example
`virt-install -x ks=kickstart-file-name.ks`.

If graphics were enabled, a VNC window will open and present the
graphical installer. If graphics were not enabled, a text installer will
appear. Proceed with the fedora installation.

[[creating-a-guest-with-virt-manager]]
Creating a guest with virt-manager
++++++++++++++++++++++++++++++++++

Start the GUI Virtual Machine Manager by selecting it from the
"Applications-->System Tools" menu, or by running the following command:

....
su -c "virt-manager"
....

If you encounter an error along the lines of "Failed to contact
configuration server; some possible causes are that you need to enable
TCP/IP networking for ORBit, or you have stale NFS locks due to a system
crash", trying running `virt-manager` not as root (without the `su -c`).
The GUI will prompt for the root password.

1.  Open a connection to a hypervisor by choosing File-->Add
connection...
2.  Choose "qemu" for KVM, or "Xen" for Xen.
3.  Choose "local" or select a method to connect to a remote hypervisor
4.  After a connection is opened, click the new icon next to the
hypervisor, or right click on the active hypervisor and select "New"
(Note - the new icon is going to be improved to make it easier to see)
5.  A wizard will present the same questions as appear with the
`virt-install` command-line utility (see descriptions above). The wizard
assumes that a graphical installation is desired and does not prompt for
this option.
6.  On the last page of the wizard there is a "Finish" button. When this
is clicked, the guest OS is provisioned. After a few moments a VNC
window should appear. Proceed with the installation as normal.

[[remote-management]]
Remote management
^^^^^^^^^^^^^^^^^

The following remote management options are available:

* (easiest) If using non-root users via SSH, then setup instructions are
at: http://wiki.libvirt.org/page/SSHSetup
* If using root for access via SSH, then create SSH keys for root, and
use `ssh-agent` and `ssh-add` before launching `virt-manager`.
* To use TLS, set up a local certificate authority and issue x509 certs
to all servers and clients. For information on configuring this option,
refer to http://wiki.libvirt.org/page/TLSSetup.

[[guest-system-administration]]
Guest system administration
^^^^^^^^^^^^^^^^^^^^^^^^^^^

When the installation of the guest operating system is complete, it can
be managed using the GUI `virt-manager` program or on the command line
using `virsh`.

[[managing-guests-with-virt-manager]]
Managing guests with virt-manager
+++++++++++++++++++++++++++++++++

Start the Virtual Machine Manager. Virtual Machine Manager is in the
"Applications-->System Tools" menu, or execute:

....
su -c "virt-manager"
....

\{1} If you are not root, you will be prompted to enter the root
password. Choose`Run unprivileged` to operate in a read-only non-root
mode.

* Choose the host you wish to manage and click "Connect" in the "Open
Connection" dialog window.
* The list of virtual machines is displayed in the main window. Guests
that are running will display a ">" icon. Guests that are not running
will be greyed out.
* To manage a particular guest, double click on it, or right click and
select "Open".
* A new window for the guest will open that will allow you to use its
console, see information about its virtual hardware and start/stop/pause
it.

For further information about `virt-manager` consult the
http://virt-manager.et.redhat.com/[project website]

Bugs in the `virt-manager` tool should be reported in
http://bugzilla.redhat.com[BugZilla] against the 'virt-manager'
component

[[managing-guests-with-virsh]]
Managing guests with virsh
++++++++++++++++++++++++++

The `virsh` command line utility that allows you to manage virtual
machines. Guests can be managed on the command line with the `virsh`
utility. The `virsh` utility is built around the libvirt management
APIl:

* `virsh` has a stable set of commands whose syntax and semantics are
preserved across updates to the underlying virtualization platform.
* `virsh` can be used as an unprivileged user for read-only operations
(e.g. listing domains, listing domain statistics).
* `virsh` can manage domains running under Xen, Qemu/KVM, esx or other
backends with no perceptible difference to the user

To start a virtual machine:

....
su -c "virsh create <name of virtual machine>"
....

To list the virtual machines currently running:

....
su -c "virsh list"
....

To list all virtual machines, running or not:

....
su -c "virsh list --all"
....

To gracefully power off a guest:

....
su -c "virsh shutdown <virtual machine (name | id | uuid)>"
....

To non gracefully power off a guest:

....
su -c "virsh destroy <virtual machine (name | id | uuid)>"
....

To save a snapshot of the machine to a file:

....
su -c "virsh save <virtual machine (name | id | uuid)> <filename>"
....

To restore a previously saved snapshot:

....
su -c "virsh restore <filename>"
....

To export the configuration file of a virtual machine:

....
su -c "virsh dumpxml <virtual machine (name | id | uuid)"
....

For a complete list of commands available for use with `virsh`:

....
su -c "virsh help"
....

Or consult the manual page: `man 1 virsh`

Bugs in the `virsh` tool should be reported in
http://bugzilla.redhat.com[BugZilla] against the 'libvirt' component.

[[other-virtualization-options]]
Other virtualization options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[[qemukvm-without-libvirt]]
QEMU/KVM without Libvirt
^^^^^^^^^^^^^^^^^^^^^^^^

QEMU/KVM can be invoked directly without libvirt, however you won't be
able to use tools such as virt-manager, virt-install, or virsh. Plain
QEMU (without KVM) can also virtualize other processor architectures
like ARM or PowerPC. See link:How_to_use_qemu[How to use qemu]

[[xen]]
Xen
^^^

Fedora can run as a Xen Guest OS and also be used as a Xen host (with
the latter being true from Fedora 16; for using an earlier version of
Fedora as a Xen Host, check out the experimental repo available at
http://myoung.fedorapeople.org/dom0). For a guide on how to install and
setup a Fedora Xen host, look at the
http://wiki.xen.org/wiki/Fedora_Host_Installation[Fedora Host
Installation] page on the Xen Project wiki.

[[openstack]]
OpenStack
^^^^^^^^^

OpenStack consists of a number services for running IaaS clouds. They
are the Object Store (Swift), Compute (Nova) and Image (Glance)
services. It is a link:Features/OpenStack[Fedora 16 feature].

[[opennebula]]
OpenNebula
^^^^^^^^^^

link:Features/OpenNebula[OpenNebula] is an Open Source Toolkit for Data
Center Virtualization.

[[ovirt]]
oVirt
^^^^^

The https://www.ovirt.org/[oVirt project] is an open virtualization
project providing a feature-rich, end to end, server virtualization
management system with advanced capabilities for hosts and guests,
including high availability, live migration, storage management, system
scheduler, and more.

[[troubleshooting-bug-reporting-and-known-issues]]
Troubleshooting, bug reporting, and known issues
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

For a list of known unresolved issues, as well as troubleshooting tips,
please see link:How_to_debug_Virtualization_problems[How to debug
virtualization problems]

Category:Documentation Category:Virtualization
'''

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