RickyZhou/Fedora7VirtQuickStart

 includes support for both the KVM and the Xen virtualization platforms. For more information on different virtualization platforms, see http://virt.kernelnewbies.org/TechComparison.

 has some significant changes and improvements since the release of Fedora Core 6. The following guide will explain how to set up Xen and KVM, and how to create and manage guests using either the command line or GUI interface.

$ grep pae /proc/cpuinfo
flags           : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow up ts
....For Intel....
flags           : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc pni monitor ds_cpl vmx est tm2 cx16 xtpr lahf_lm

....For AMD....
flags           : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm cr8_legacy
, Xen can be installed by selecting Virtualization in the Base Group in the installer.

 installation, the Xen kernel and tools can be installed by running the following command:

This installs the required packages and their dependencies.  'kernel-xen' contains the Xen-enabled kernel for both the host and guest operating systems as well as the hypervisor.  Also, the 'xen' package will be installed, which contains the user-space tools for interacting with the hypervisor.

Once this is done, there should be an entry in the file <code>/boot/grub/grub.conf</code> for booting the <code>xen</code> kernel. The <code>xen</code> kernel is '''not''' set as the default boot option.

To set GRUB to boot with <code>kernel-xen</code> by default, edit <code>/boot/grub/grub.conf</code> and set the default to the xen [[FootNote(Note that future kernel-xen packages can be set to the default kernel by editing <code>/etc/sysconfig/kernel</code>)]  

This is an example <code>/boot/grub/grub.conf</code> configured to boot into the Xen hypervisor:

<pre>
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Fedora (2.6.20-2925.5.fc7xen)
root (hd0,0)
kernel /xen.gz-2.6.20-2925.5.fc7
module /vmlinuz-2.6.20-2925.5.fc7xen ro root=/dev/VolRoot/LogVolRoot rhgb quiet
module /initrd-2.6.20-2925.5.fc7xen.img
title Fedora (2.6.20-1.3084.fc7)
root (hd0,0)
kernel /vmlinuz-2.6.20-1.3084.fc7 ro root=/dev/VolRoot/LogVolRoot rhgb quiet
initrd /initrd-2.6.20-1.3084.fc7.img
, KVM can be installed by selecting KVM in the Base Group in the installer.

 installations, the KVM package and virtualization tools can be installed by running the following command:

This installs the required packages and their dependencies.  Note that KVM is included in the regular kernel; booting into a special kernel is not required.

== Enabling Xen ==

Once the system is booted into the Xen kernel, check to verify the kernel and that Xen is running:

<pre>
2.6.20-2925.5.fc7xen

Name                              ID Mem(MiB) VCPUs State  Time(s)
Domain-0                           0      610     1 r----- 12492.1
/ installation of Fedora 25
 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.

The following questions about the new guest OS will be presented. This information can also be passed as command line options; run with an argument of <code>--help</code> for more details.  In particular, kickstart options can be passed with <code>-x ks=options</code>.

1. What is the name of your virtual machine?  This is the label that will identify the guest OS. This label will be used for various <code>xm</code> commands and also appear in <code>virt-manager</code> the Gnome-panel Xen applet. In addition, it will be the name of the <code>/etc/xen/<name></code> file that stores the guest's configuration information.
1. How much RAM should be allocated (in megabytes)?  This is the amount of RAM to be allocated for the guest instance in megabytes (eg, 256).  Note that installation with less than 256 megabytes is not recommended.
1. What would you like to use as the disk (path)?  The local path and file name of the file to serve as the disk image for the guest (eg, /home/joe/xenbox1).  This will be exported as a full disk to your guest.
1. How large would you like the disk to be (in gigabytes)? The size of the virtual disk for the guest (only appears if the file specified above does not already exist).  4.0 gigabytes is a reasonable size for a "default" install
1. Would you like to enable graphics support (yes or no): Should the graphical installer be used?
1. What is the install location?  This is the path to a Fedora {{Template:DocsDict/BeatsVer}}
  installation tree in the format used by anaconda.  NFS, FTP, and HTTP locations are all supported.  Examples include:
  * <code>nfs:my.nfs.server.com:/path/to/test2/tree/</code>
* <code>http://my.http.server.com/path/to/tree/</code>
* <code>ftp://my.ftp.server.com/path/to/tree</code>

{{Template:Note}} Installation must be a network type. It is not possible to install from a local disk or CDROM. It is possible, however, to set up an installation tree on the host OS and then export it as an NFS share.

The installation will then commence. If graphics were enabled, a VNC window will open and present the graphical installer. If graphics were not enabled, the standard text installer will appear. Proceed as normal with the installation.

=== Building a Fedora Guest System using <code>virt-manager</code> ===

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

1. Choose "Local Xen Host" and click "Connect" in the "Open Connection" dialog window.
1. Click the "New" button at the bottom of the <code>virt-manager</code> window, or select File-->New.
1. A wizard will present the same questions as appear with the <code>virt-install</code> command-line utility (see descriptions above). The wizard assumes that a graphical installation is desired and does not prompt for this option.
1. 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.

=== Building a Fedora Guest System using 'cobbler' and 'koan' ===

Cobbler is a tool for configuring a provisioning server for PXE, Xen, and existing systems. See http://cobbler.et.redhat.com for details.  The following instructions are rather minimal and more configuration options are available.

First, set up a provisioning server:

<pre>
yum install cobbler
man cobbler # read the docs!
cobbler check # validate that the system is configured correctly
cobbler distro add --name=myxendistro --kernel=/path/to/vmlinuz --initrd=/path/to/initrd.img
cobbler profile add --name=myxenprofile --distro==myxendistro [--kickstart=/path/to/kickstart] 
cobbler list # review the configuration
cobbler sync # apply the configuration to the filesystem
cobbler import --mirror=rsync://your-fedora-mirror --mirror-name=fedoracobbler sync

yum install koan
koan --virt --profile=myxenprofile --server=hostname-of-cobbler-server

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

* Choose "Local Xen Host" and click "Connect" in the "Open Connection" dialog window.
* The list of virtual machines is displayed in the main window. The first machine is called "Domain 0"; this is the host computer.
* If a machine is not listed, it is probably not running. To start up a machine select "File-->Restore a saved machine..." and select the file that serves as the guest's disk.
* The display lists the status, CPU and memory usage for each machine. Additional statistics can be selected under the "View" menu.
* Double click the name of a machine to open the virtual console.
* From the virtual console, select "View-->Details" to access the machine's properties and change its hardware configuration
* To access the serial console (if there is a problem with the graphical console) select "View-->Serial Console"

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

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

=== Managing Virtual Machines from the command line with <code>virsh</code> ===

Virtual machines can be managed on the command line with the <code>virsh</code> utility. The <code>virsh</code> utility is built around the libvirt management API and has a number of advantages over the traditional Xen <code>xm</code> tool:

* virsh has a stable set of commands whose syntax & semantics will be preserved across updates to Xen.
* virsh can be used as an unprivileged user for read-only operations (eg listing domains, getting info, etc)
* virsh will (in future) be able to manage QEMU, VMWare, etc machines in additional to Xen, since libvirt is hypervisor agnostic.

To start a new virtual machine from an XML vm definition:

<pre>

To list the virtual machines currently running, use:

<pre>

To gracefully power off a guest use:
<pre>

To save a snapshot of the machine to a file of your choosing:
<pre>

To restore a previously saved snapshot:
<pre>

To export the XML config associated with a virtual machine:
<pre>

For a complete list of commands available for use with <code>virsh</code> run:
<pre>

Or consult the manual page <code>virsh(1)</code>

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

=== Managing Virtual Machines from the command line with <code>qemu-kvm</code> ===

KVM virtual machines can be managed in the command line using the 'qemu-kvm' command.

=== Managing Virtual Machines from the command line with <code>xm</code> ===

In addition to the <code>virsh</code> command, virtual machines can also be managed on the command line with the Xen-specific <code>xm</code> utility. To power on a virtual machine and attach a serial console, use:

<pre>

To list the virtual machines currently running, use:

<pre>

To power off a guest use:
<pre>

To save a snapshot of the machine to a file:
<pre>

To restore a previously saved snapshot:
<pre>

To display <code>top</code>-like statistics for all running machines:
<pre>

For a complete list of commands available for use with <code>xm</code> run:
<pre>

Bugs in the <code>xm</code> tool should be reported in [http://bugzilla.redhat.com BugZilla]  against the 'xen' component

= Troubleshooting =

== SELinux ==

The SELinux policy in Fedora {{Template:DocsDict/BeatsVer}}
  has the neccessary rules to allow use of Xen with SELinux enabled. The main caveat to be aware of is that any file backed disk images need to be in a special directory - /var/lib/xen/images.  This applies both to regular disk images, and ISO images.  Block device backed disks are already labelled correctly to allow them to pass SELinux checks.

== Log files ==

There are two log files stored on the host system to assist with debugging Xen related problems. The file <code>/var/log/xen/xend.log</code> holds the same information reported with '<code>xm log</code>. Unfortunately these log messages are often very short and contain little useful information. The following is the output of trying to create a domain running the kernel for NetBSD/xen.

<pre>
[2005-06-27 02:23:02 xend]  ERROR (SrvBase:163) op=create: Error creating domain:(0, 'Error')
Traceback (most recent call last):
File "/usr/lib/python2.4/site-packages/xen/xend/server/SrvBase.py", line 107, in _perform
val = op_method(op, req)
File "/usr/lib/python2.4/site-packages/xen/xend/server/SrvDomainDir.py", line 71, in op_create
raise XendError("Error creating domain: " + str(ex))
XendError: Error creating domain: (0, 'Error')
ERROR: Will only load images built for Xen v3.0
ERROR: Actually saw: 'GUEST_OS=netbsd,GUEST_VER=2.0,XEN_VER=2.0,LOADER=generic,BSD_SYMTAB'
ERROR: Error constructing guest OS
xm dmesg
title Fedora Core (2.6.17-1.2600.fc6xen)
root (hd0,2)
kernel /xen.gz-2.6.17-1.2600.fc6 com1=38400,8n1 sync_console
module /vmlinuz-2.6.17-1.2600.fc6xen ro root=LABEL=/ rhgb quiet console=ttyS0 console=tty pnpacpi=off
module /initrd-2.6.17-1.2600.fc6xen.img

Will log output from /dev/ttyS0 into a file /var/log/ttywatch/myhost.log

=== Paravirt guest serial console access ===

Para-virtualized guest OS will automatically have a serial console configured, and plumbed through to the Domain-0 OS. This can be accessed from the command line using

<pre>

Alternatively, the graphical <code>virt-manager</code> program can display the serial console. Simply display the 'console' or 'details' window for the guest & select 'View -> Serial console' from the menu bar.

=== Fullyvirt guest serial console access ===

Fully-virtualized guest OS will automatically have a serial console configured, but the guest kernel will not be configured to use this out of the box. To enable the guest console in a Linux fully-virt guest, edit the /etc/grub.conf in the guest and add 'console=ttyS0 console=tty0'. This ensures that all kernel messages get sent to the serial console, and the regular graphical console. The serial console can then be access in same way as paravirt guests:

<pre>

Alternatively, the graphical <code>virt-manager</code> program can display the serial console. Simply display the 'console' or 'details' window for the guest & select 'View -> Serial console' from the menu bar.

== Accessing data on a guest disk image ==

There are two tools which can help greatly in accessing data within a guest disk image: ''lomount'' and ''kpartx''.

{{Template:Warning}} Remember never to do this while the guest is up and running, as it could corrupt the filesystem:

* '''lomount'''

<pre>

lomount only works with small disk images and cannot deal with LVM volumes, so for more complex cases, kpartx (from the ''device-mapper-multipath'' RPM) is preferred:

* '''kpartx'''

<pre>
add map guest1p1 : 0 208782 linear /dev/xen/guest1 63
add map guest1p2 : 0 16563015 linear /dev/xen/guest1 208845
/dev/loop0
add map loop0p1 : 0 208782 linear /dev/loop0 63
add map loop0p2 : 0 12370050 linear /dev/loop0 208845
brw-rw---- 1 root disk 253,  6 Jun  6 10:32 xen-guest1
brw-rw---- 1 root disk 253, 14 Jun  6 11:13 guest1p1
brw-rw---- 1 root disk 253, 15 Jun  6 11:13 guest1p2

To access LVM volumes on the second partition, rescan LVM with <code>vgscan</code> and activate the volume group on that partition (named "VolGroup00" by default) with <code>vgchange -ay</code>:

<pre>
Reading all physical volumes.  This may take a while...
Found volume group "VolGroup00" using metadata type lvm2
2 logical volume(s) in volume group "VolGroup00" now active
LV        VG         Attr   LSize   Origin Snap%  Move Log Copy%
LogVol00  VolGroup00 -wi-a-   5.06G
LogVol01  VolGroup00 -wi-a- 800.00M
...

{{Template:Warning}} Note: '''always''' remember to deactivate the logical volumes with "vgchange -an", remove the partitions with "kpartx -d", and (if appropriate) delete the loop device with "losetup -d" after performing the above steps. The default volume group name for a Fedora install is always the same, it is important to avoid activating two volume group of the same name at the same time.  LVM will cope as best it can, but it is not possible to distinguish between these two groups on the command line. In addition, if the volume group is active on the host and the guest at the same time, it can cause filesystem corruption.

== Frequently Asked Questions ==

* Q: I am trying to start the xend service and nothing happens, then when I do a <code>xm list1 I get the following:

<pre>
Error: Error connecting to xend: Connection refused.  Is xend running?
ERROR: Could not obtain handle on privileged command interface (2 = No such file or directory)
Traceback (most recent call last):
File "/usr/sbin/xend", line 33, in ?
from xen.xend.server import SrvDaemon
File "/usr/lib/python2.4/site-packages/xen/xend/server/SrvDaemon.py", line 21, in ?
import relocate
File "/usr/lib/python2.4/site-packages/xen/xend/server/relocate.py", line 26, in ?
from xen.xend import XendDomain
File "/usr/lib/python2.4/site-packages/xen/xend/XendDomain.py", line 33, in ?
import XendDomainInfo
File "/usr/lib/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 37, in ?
import image
File "/usr/lib/python2.4/site-packages/xen/xend/image.py", line 30, in ?
xc = xen.lowlevel.xc.xc()
RuntimeError: (2, 'No such file or directory')

Search

RickyZhou/Fedora7VirtQuickStart

Contents

Virtualization in Fedora 7

Quick Start

System Requirements

Requirements for Para-virtualized Guests

Fully-virtualized guests (HVM/Intel-VT/AMD-V)

Conventions

Installing the Xen Software

Installing the KVM Software

Enabling KVM

Building a Fedora Guest System

Building a Fedora Guest System using `virt-install`

After Installation

Managing Virtual Machines graphically with `virt-manager`

Serial Console

Host serial console access

Getting Help

References

Footnotes

Search

RickyZhou/Fedora7VirtQuickStart

Virtualization in Fedora 7

Quick Start

System Requirements

Requirements for Para-virtualized Guests

Fully-virtualized guests (HVM/Intel-VT/AMD-V)

Conventions

Installing the Xen Software

Installing the KVM Software

Enabling KVM

Building a Fedora Guest System

Building a Fedora Guest System using virt-install

After Installation

Managing Virtual Machines graphically with virt-manager

Serial Console

Host serial console access

Getting Help

References

Footnotes

Building a Fedora Guest System using `virt-install`

Managing Virtual Machines graphically with `virt-manager`