KVM

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Check that your CPU supports hardware virtualization

Для запуска KVM, процессор должен быть с поддержкой аппаратной виртуализации. Intel и AMD и разработали расширения для своих процессоров, соответственно Intel VT-х (кодовое название Vanderpool) и AMD-V (кодовое название Pacifica). Чтобы убедиться, что ваш процессор поддерживает один из них, вы можете просмотреть результаты этой команды: 

   egrep -c '(vmx|svm)' /proc/cpuinfo

0 означает что CPU не поддерживает аппаратную виртуализацию.
1 (или более) означает что CPU поддерживает аппаратную виртуализацию, но предварительно необходимо убедиться что виртуализация разрешена в BIOS.

Также на Ubuntu системах можно запустить команду kvm-ok. Вывод будет примерно такой: 

INFO: /dev/kvm does not exist
HINT:   sudo modprobe kvm_intel
INFO: Your CPU supports KVM extensions
KVM acceleration can be used

Use a 64 bit kernel (if possible)

Использование 64-битного ядра на хостовой системе рекомендуется, но не обязательно. Для того чтобы выделить более 2GB памяти для VMs (виртуальных машин), необходимо использовать 64-битное ядро. С установленным 32-битным ядром максимально возможное количество памяти, которое может быть выделено виртуальной машине, будет ограничено 2 GB. Также на 64-битной системе можно создавать как 32-битные виртуальные машины так и 64-битные. 32-битная система позваоляет создавать только 32-битные виртуальные машины. Проверить поддержку 64-битных систем процессором можно запустив следующую команду: 

egrep -c ' lm ' /proc/cpuinfo

0 - означает, что процессор не 64-битный
1 или более означает что процессор 64-битный. Note: lm stands for Long Mode which equates to a 64-bit CPU.

Установка KVM

Установка необходимых пакетов

В следующем примере подразумевается, что KVM устанавливается на системе без установленного X сервера (т.е. отсутствует графический режим). Необходимо установить следующие пакеты: Lucid (10.04) и старше: 

  sudo apt-get install qemu-kvm libvirt-bin ubuntu-vm-builder bridge-utils virtinst

Karmic (9.10) и более ранние версии: 

  sudo aptitude install kvm libvirt-bin ubuntu-vm-builder bridge-utils virtinst
  • libvirt-bin предоставляет libvirtd, которая необходима для администрирования qemu и kvm виртуальных машины используя libvirt
  • qemu-kvm (kvm в Karmic и ранних версиях) - backend
  • ubuntu-vm-builder мощное средство командной строки для создания виртуальных машин
  • bridge-utils предоставляет мост с внешней сети для виртуальных машин

Вы также можете установит virt-viewer, для просмотра виртуальных машин.

  • Загружаем KVM kernel module
modprobe -a kvm
modprobe -a kvm_intel
lsmod  | grep -i kvm
kvm_intel              61643  4 
kvm                   384000  1 kvm_intel

Настройка сети для KVM

Существует несколько способов разрешить виртуальным машинам доступ во внешнюю сеть:

  • The default virtual network configuration is known as Usermode Networking. Traffic is NATed through the host interface to the outside network.
  • Alternately, you can configure Bridged Networking to enable external hosts to directly access services on the guest operating system.

Usermode Networking

В дефолтной настройке, гостевые системы будут иметь доступ к сетевым сервисам, но не будут видны остальным машинам в сети. Например гостевая система будет иметь возможность просматривать Web, но не будет способна иметь доступный из внешней сети Web-сервер.

По умолчанию, гостевая ОС получит IP адрес в 10.0.2.0/24 диапазоне и будет доступна по адресу 10.0.2.2. You should be able to ssh into the host OS (at 10.0.2.2) from inside the guest OS and use scp to copy files back and forth.

Если данная конфигурация подходит для ваших целей - никакие дополнительные настройки не нужны.

Usermode Networking

Assign CAP_NET_ADMIN Capability

Creating a network bridge on the host

nstall the bridge-utils package: 

sudo apt-get install bridge-utils

We are going to change the network configuration1. To do it properly, you should first stop networking2: 

sudo invoke-rc.d networking stop

If you are on a remote connection, and so cannot stop networking, go ahead with the following commands, and use sudo invoke-rc.d networking restart at the end. If you make a mistake, though, it won't come back up.

To set up a bridge interface, edit /etc/network/interfaces and either comment or replace the existing config with (replace with the values for your network): 

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual

auto br0
iface br0 inet static
        address 192.168.0.10
        network 192.168.0.0
        netmask 255.255.255.0
        broadcast 192.168.0.255
        gateway 192.168.0.1
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0
        bridge_maxwait 0

or to use DHCP 

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual

auto br0
iface br0 inet dhcp
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0
        bridge_maxwait 0

This will create a virtual interface br0.

Now restart networking: 

sudo /etc/init.d/networking restart

If your VM host "freezes" for a few seconds after starting or stopping a KVM guest when using bridged networking, it is because a Linux bridge will take the hardware address of the lowest numbered interface out of all of the connected interface. To work around this, add the following to your bridge configuration: 

post-up ip link set br0 address f4:6d:04:08:f1:5f

and replace f4:6d:04:08:f1:5f with the hardware address of a physical ethernet adapter which will always be part of the bridge.

Создание гостевой системы

virt-install позволяет загрузить iso образ и установить практически любую ОС. Список поддерживаемых операционных систем можно увидеть на официальном сайте KVM: 

http://www.linux-kvm.org/page/Guest_Support_Status

Ниже будет приведено несколько примеров установки различных ОС. Существуют некоторые проблемы в процессе установки, так что ниже будут предоставлены несколько путей решения их.

  • Подготовка дискового образа гостевой системы
    • Если используем LVM то можно подготовить образ по инструкции Understanding LVM
    • Если используем файл в качестве образа гостевой системы то стоит использовать например следующие параметры --disk path=/var/lib/libvirt/images/guest.img,size=10. При этом для образа гостевой системы будет автоматически создан файл размеров 10GB
  • Загрузка/Установка гостевой системы будет осуществляться с ISO образа, поэтому его необходимо заранее скачать и в некоторых случаях смонтировать в удобное место.
  • Создание гостевой новой гостевой системы с последующей установкой CentOS 6 в текстовом режиме:
   virt-install --name ${NewVMName} --vcpus ${NumberOfCPU} --ram ${RAM_Size_in_MB} \
   --disk path=/dev/${VolumeGroupName}/${LogicalVolumeName} -l ${Path_To_ISO_Image_MountPoint} \
   -v --accelerate --os-type linux \
   --network=bridge:${NetworkBridgeName} --nographics -x "console=ttyS0"

создание новой гостевой системы и установки CentOS 6 в автоматическом режиме с использованием Kickstart файла: 

   
   virt-install --name ${NewVMName} --vcpus ${NumberOfCPU} --ram ${RAM_Size_in_MB} \
   --disk path=/dev/${VolumeGroupName}/${LogicalVolumeName} -l ${Path_To_ISO_Image_MountPoint} \
   -v --accelerate --os-type linux \
   --network=bridge:${NetworkBridgeName} --nographics \
   -x "console=ttyS0 ks=${kickstart_file_URL} ksdevice=eth0 ip=${ServerIP} netmask=${NetMask} dns=${ResolverIP} gateway=${GatewayIP}" \

Сгенерировать Kickstart file можно например используя графические средство system-config-kickstart
Для установки CentOS 6 по сети, можно использовать следующее зеркало: 

http://mirror.centos.org/centos-6/6/os/x86_64/
  • Создание гостевой новой гостевой системы с последующей установкой Win7:
    virt-install --name=Win7.vm --ram=1024 --vcpus=2 -v \
    --cdrom /media/iso/Windows_7_Ultimate_RU_x86_and_x64_\(Build_7600\).iso --disk path=/dev/vmarea/Win7 \
    --accelerate --network=bridge:br0 --vnc --noautoconsole \

Usefull extra parameters

  • Setting up a static IP for installation using kickstart:
ks=${kickstart_file_URL} ksdevice=eth0 ip=${ServerIP} netmask=${NetMask} dns=${ResolverIP}
  • Obraint IP from DHCP for installation using kickstart:
ks=${kickstart_file_URL} ksdevice=eth0 ip=dhcp
  • Disable ipv6 support
noipv6

Клонирование гостевой системы

  • Для клонирования гостевой системы можно использовать следующую команду:
virt-clone -o ${ORIGINAL_GUEST} -n ${NEW_GUEST_NAME} -f /dev/${VolumeGrouP}/${NEW_GUEST_LogicalVolume_Name}

Hints/FAQ/HOWtos

Migrate from LVM disk image to file disk image

  • Copy LVM image to file:
dd if=/dev/home/node1 of=/var/lib/libvirt/images/node1.img bs=512
  • Modify the guest system config:
virsh edit node1

change 

<disk type='block' device='disk'>

to 

<disk type='file' device='disk'>

and change 

<source dev='/dev/VG/node1'/>

to 

<source file='/var/lib/libvirt/images/node1.img'/><pre>

===How to change a domain memory limit===
* Checking the current domain limits:
<pre>
root@workstation:~# virsh dominfo node1
Id:             -
Name:           node1
UUID:           5b870745-2cea-f658-9548-1b9711ccb0ba
OS Type:        hvm
State:          shut off
CPU(s):         2
Max memory:     2097152 kB
Used memory:    2097152 kB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: apparmor
Security DOI:   0

or 

root@workstation:~# grep -i memory /etc/libvirt/qemu/node1.xml 
  <memory>2097152</memory>
  <currentMemory>2097152</currentMemory>
  • Set the needed memory limit in Kilobytes:
virsh setmaxmem node1 4194304

or edit directly the configuration file

  • Checking results
virsh dominfo node1
Id:             -
Name:           node1
UUID:           5b870745-2cea-f658-9548-1b9711ccb0ba
OS Type:        hvm
State:          shut off
CPU(s):         2
Max memory:     4194304 kB
Used memory:    2097152 kB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: apparmor
Security DOI:   0

How to change a domain vCPU limit

  • Shutdown a domain
virsh shutdown node1
  • Edit the domain xml configuration file
vim /etc/libvirt/qemu/node1.xml
  • Restart libvrt daemon
/etc/init.d/libvirt-bin restart
  • Check results
virsh vcpuinfo node1
VCPU:           0
CPU:            N/A
State:          N/A
CPU time        N/A
CPU Affinity:   yyyy

How to disable virbr0 NAT Interface

The virtual network (virbr0) used for Network address translation (NAT) which allows guests to access to network services. However, NAT slows down things and only recommended for desktop installations. To disable Network address translation (NAT) forwarding type the following commands: Display Current Setup

Type the following command: 

ifconfig

Sample outputs: 

virbr0    Link encap:Ethernet  HWaddr 00:00:00:00:00:00
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:39 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:7921 (7.7 KiB)

Or use the following command: 

 virsh net-list

Sample outputs: 

Name                 State      Autostart
-----------------------------------------
default              active     yes

To disable virbr0, enter: 

   virsh net-destroy default
   virsh net-undefine default
   service libvirtd restart
   ifconfig

Redirect FreeBSD Console To A Serial Port

'm using KVM to run multiple virtual machines under Redhat Enterprise Linux server 5.5. I've installed FreeBSD 7.x 64 bit as guest operating systems. How do I redirect the FreeBSD version 6, 7 or 8 virtual machine console to a serial port using virsh console command for management purpose from host itself?

FreeBSD does support a dumb terminal on a serial port as a console. This is useful for quick login or debug guest system problem without using ssh. First, login as root using ssh to your guest operating systems: 

   ssh root@freebsd.guest.com

Edit /boot/loader.conf, enter: 

   vi /boot/loader.conf

Append the following entry: 

   console="comconsole"

Save and close the file. Edit /etc/ttys, enter: 

   vi /etc/ttys

Find the line that read as follows: 

   ttyd0  "/usr/libexec/getty std.9600"   dialup  off secure

Update it as follows: 

   ttyd0   "/usr/libexec/getty std.9600"   vt100   on secure

Save and close the file. Reboot the guest, enter: 

   reboot

After reboot, you can connect to FreeBSD guest as follows from host (first guest the list of running guest operating systems): 

   virsh list

Sample outputs: 

 Id Name                 State
----------------------------------
 4 freebsd              running

Now, connect to Freebsd guest, enter: 

   virsh console 4

OR 

   virsh console freebsd

KVM migration

Requirements

1. A virtualized guest installed on shared networked storage using one of the following protocols:

  • Fibre Channel
  • iSCSI
  • NFS
  • GFS2

2. Both systems must have identical network configurations. All bridging and network configurations must be exactly the same on both hosts.
3. Shared storage must mount at the same location on source and destination systems. The mounted directory name must be identical.

KVM live migration

  • Share guest's disk image via NFS (iSCSI if possible):
cat /etc/exports
/var/lib/libvirt/images 192.168.1.0/24(rw,no_root_squash,async)
  • Mount exported FS in the same place on destination server
root@destination.server.com:~# mount source.server.com:/var/lib/libvirt/images /var/lib/libvirt/images
  • On the source server run:
virsh migrate --live guest qemu+ssh://destination.server.com/system
  • Stop the guest and copy guest's disk image to the destiong server:
rsync --progress -av --inplace /var/lib/libvirt/images/guest.img /var/lib/libvirt/migration/guest.img
umount /var/lib/libvirt/images/
mv /var/lib/libvirt/migration/guest.img /var/lib/libvirt/images/guest.img
  • That's it

Linux kvm private switch

  • Create a network xml file
<network>
  <name>private</name>
  <bridge name='virbr0' stp='on' delay='0' />
  <mac address='52:54:00:54:95:EE'/>
  <ip address='10.20.0.1' netmask='255.255.255.0'>
  </ip>
</network>
  • Import the network xml file
 # virsh net-define /tmp/privatenet.xml 
Network privatenet created from /tmp/privatenet.xml
  • Verify that the network is created in libvirt
[root@vicky]# virsh net-list --all
Name State Autostart
-----------------------------------------
default active yes
privatenet active no

[root@vicky] # virsh net-info privatenet
Name privatenet
UUID b13de960-72cc-4f66-32df-432ce2e45538
Active: yes Persistent: no
Autostart: no
Bridge: privatebr0
  • Enable auto-start
 virsh net-list
Name State Autostart
-----------------------------------------
default active yes 

virsh # net-list --all
Name State Autostart
-----------------------------------------
default active yes 
privatenet inactive no 

virsh # net-start privatenet
Network privatenet started

virsh # net-autostart privatenet
Network privatenet marked as autostarted

virsh #
  • Start the domain in virt-manager or by virsh
    # virsh
    Welcome to virsh, the virtualization interactive terminal.

    Type: 'help' for help with commands
     'quit' to quit

    virsh # list --all
     Id Name State
    ----------------------------------
     - centos6 shut off
     - debian shut off
     - fed1 shut off
     - fed2 shut off
     - mywin shut off
     - sol10 shut off

    virsh # start fed1
    Domain fed1 started

    virsh #
  • Original article:
http://www.wagemakers.be/english/doc/linux_kvm_private_virtual_switch

KVM snapshot

  • Если образ виртуальной машины в raw(file) формате, то нужно его конвертировать в qcow2(file format for disk image files used by QEMU), т.к. raw снапшоты не поддерживает. Перевести в формат qcow2 можно следующей командой:
qemu-img convert -O qcow2 image.img image_new.qcow
  • Затем необходимо отредактировать xml конфигурационый файл виртуальной машины: 
virsh edit <guest-name>

и правим type и путь к образу. Например: 

   <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/centos-6.qcow'/>
      <target dev='hda' bus='ide'/>
      <address type='drive' controller='0' bus='0' unit='0'/>
    </disk>
  • Узнать детальную информацию образа ВМ.
qemu-img info image.qcow
  • создать снапшот виртуальной машины
virsh snapshot-create <имя вм>
  • откатиться к нужному снапшоту
virsh snapshot-revert <имя вм> <номер снапшота вм> -
  • список снапшотов для данной виртуальной машины можно посмотреть командой:
virsh snapshot-list <имя вм>

KVM guest boot priority

  • Modify boot priority:
  <os>
    <type arch='x86_64' machine='pc-1.0'>hvm</type>
    <boot dev='cdrom'/>
    <boot dev='hd'/>
  </os>
  • Add cdrom device:
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/home/libvirt/iso/centos-6.4.iso'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1' unit='0'/>
    </disk>

KVM guest + OVS

Setup vSwitch

Technically the virtual switch is a type of bridge, but do not try to manage it with the tools provided by net-misc/bridge-utils. They are not aware of how this type of bridge works. There is a compatibility mode for Open vSwitch that allows the virtual switch to be managed by the bridge-utils. However that is outside the scope of this article.

  • First, create the bridge. We'll call it "vbr0".
root # ovs-vsctl add-br vbr0
  • Next, we will add eth1 to this bridge.
root # ovs-vsctl add-port vbr0 eth1
  • The final change we need to make is to assign the bridge a controller. Without it, the bridge doesn't know what to do with the packets.
root # ovs-vsctl set-controller vbr0 ptcp:

The "ptcp:" option is set to match how the controller is setup in /etc/conf.d/ovs-controller, which by default is configured to listen to IP socket connections on port 6633. If you are only using the controller on the local machine, you can set the controller to use a unix domain sockets. Generally, unix domain sockets are more light-weight with less overhead than IP sockets, so they can provide faster communication between controller and bridge. If you want to go that route, you need to configure both the controller and bridge to use a unix socket. Please refer to the man pages for more details.

  • One setting that is optional, but very highly recommended, is to turn on the spanning tree protocol.
root # ovs-vsctl set bridge vbr0 stp_enable=true

You will want to be sure the spanning tree protocol (stp) is enabled in your hardware routers and switchers as well.

Setup libvirt

Recent versions of libvirt support this type of bridge, we just have to configure the virtual machine to use it.
  • Connect to the local QEMU manager:
root # virsh --connect qemu:///system
  • Once logged into the virsh shell, get a listing of the virtual machines:
root # list --all
  • Select the virtual machine you need to configure:
root # edit foo-vm

This will open up the xml config in your default text editor. Find the section that defines the virtual OS's network interfaces. It will usually look like something similar to this: 

    <interface type='network'>
      <source network='default'/>
    </interface>

There will probably be a few other tags inside the <interface> tag, however, we are only showing the ones you will need to change. They will need to change to the following: 

    <interface type='bridge'>
      <source bridge='vbr0'/>
      <virtualport type='openvswitch' />
    </interface>

If you virtual machines is setup up with more than one network interface, you will need to edit each additional network interface tag accordingly. Save the file and exit. You will return to the virsh shell, which should confirm that the virtual machine config has been updated.

  • Start the virtual machine:
root # start foo-vm

Mounting raw image files and kpartx

  • list partitions that are to be found on that drive image.
# kpartx -l gothbook.img
loop1p1 : 0 512000 /dev/loop1 63
loop1p2 : 0 512000 /dev/loop1 512063
loop1p3 : 0 45056000 /dev/loop1 1024063
loop1p5 : 0 8388608 /dev/loop1 46090548
loop1p6 : 0 39070017 /dev/loop1 54492543
loop1p7 : 0 62733762 /dev/loop1 93562623

I can see from the output of kpartx that my drive image contains 6 partitions. I can see their starting offsets. The first column tells me the names of the device files that will be created if I choose to add these device partitions. Lets add them now. 

# kpartx -a -v gothbook.img
add map loop1p1 (253:6): 0 512000 linear /dev/loop1 63
add map loop1p2 (253:7): 0 512000 linear /dev/loop1 512063
add map loop1p3 (253:8): 0 45056000 linear /dev/loop1 1024063
add map loop1p5 (253:9): 0 8388608 linear /dev/loop1 46090548
add map loop1p6 (253:10): 0 39070017 linear /dev/loop1 54492543
add map loop1p7 (253:11): 0 62733762 linear /dev/loop1 93562623

# ls -l /dev/mapper
total 0
crw-rw---- 1 root root  10, 62 2010-06-15 17:40 control
brw-rw-r-- 1 neil neil 253,  6 2010-08-16 00:28 loop1p1
brw-rw-r-- 1 neil neil 253,  7 2010-08-16 00:28 loop1p2
brw-rw-r-- 1 neil neil 253,  8 2010-08-16 00:28 loop1p3
brw-rw-r-- 1 neil neil 253,  9 2010-08-16 00:28 loop1p5
brw-rw-r-- 1 neil neil 253, 10 2010-08-16 00:28 loop1p6
brw-rw-r-- 1 neil neil 253, 11 2010-08-16 00:28 loop1p7

The preceding command added six device map files to /dev/mapper. Each of these device files corresponds to a partition from that hard drive image. We can now use these device files to mount these partitions and access any files they contain. I want to mount the fifth partition (/dev/mapper/loop1p6) and have a look at its files. 

# mkdir /mnt/sysimage
 
# mount /dev/mapper/loop1p6 /mnt/sysimage
# ls /mnt/sysimage
bin    dev   initrd.img      lost+found  opt   sbin     sys  var
boot   etc   initrd.img.old  media       proc  selinux  tmp  vmlinuz
cdrom  home  lib             mnt         root  srv      usr  vmlinuz.old

After mounting the device file, you can access the files contained on that partition. When you are done, don’t forget to umount the partition and disconnect the device map files using kpartx. 

# umount /mnt/sysimage
# kpartx -d -v gothbook.img

VNC configuration for guest

With the -vnc option option, you can have QEMU listen on VNC display display and redirect the VGA display over the VNC session. When using the VNC display, you must use the -k parameter to set the keyboard layout if you are not using en-us. Valid syntax for the display is as follows: <sytanxhighlight lang="bash"> -vnc :0 -vnc 192.168.1.5:0 -vnc 0.0.0.0:5 -vnc 0.0.0.0:1 -k en-us

        1. Require that password based authentication is used for client connections ####

-vnc 0.0.0.0:1,password -k en-us </sytanxhighlight> In the following example start centos1 guest vm using vnc 

 /usr/libexec/qemu-kvm -S -M rhel5.4.0 -m 1024 -smp 1 -vnc 0.0.0.0:1 -k en-us -name centos1 -monitor pty -boot c -drive file=/var/lib/libvirt/images/centos1.img

I this particular case VNC server will listen on port 5901 and when you connect to VM with VNC client you should specify port 1. If you use SSH tunnel the tunneled port should be 5901.

Another method to set VNC settings in guest system XML file: 

    <graphics type='vnc' port='5902' autoport='yes' listen='127.0.0.1' keymap='en-us'>
      <listen type='address' address='127.0.0.1'/>
    </graphics>

Where,

  • type='vnc': The graphics element has a mandatory type attribute which takes the value "sdl", "vnc", "rdp" or "desktop". In this case it is set to VNC for remote access.
  • autoport='yes': The autoport attribute is the new preferred syntax for indicating autoallocation of the TCP port to use.
  • passwd='YOUR-PASSWORD-HERE': The passwd attribute provides a VNC password in clear text.
  • keymap='en-us': The keymap attribute specifies the keymap to use.
  • listen='127.0.0.1': The listen attribute is an IP address for the server to listen on.

Hypervisor memory and cpu usage stats

  • Get KVM Hypervisor(Host) Memory info
virsh nodememstats
 
Output:
 
total : 8027952 KiB
free : 2772452 KiB
buffers: 264476 KiB
cached : 1677176 KiB
  • Get KVM Hypervisor CPU info
virsh nodecpustats
 
Output:
 
user: 3916550000000
system: 1183160000000
idle: 21003220000000
iowait: 655350000000

Note: The above numbers are in nanoseconds of time available for user/system/idle etc.

If you want we can even get individual CPU, if you have more than 1 CPU. Suppose if we want to get CPU2 details use –cpu 1 for that 

virsh nodecpustats –cpu 1
 
Output:
user: 1131610000000
system: 348770000000
idle: 5141870000000
iowait: 136620000000

How about getting the values in percentage of total CPU available? 

virsh nodecpustats –percent
 
Output:
 
usage: 20.3%
user: 17.5%
system: 2.8%
idle: 79.7%
iowait: 0.0%

Documentation

General docs

cpnfigure KVM in Ubuntu
CentOS / Redhat: Install KVM Virtualization Software
KVM Virtualization: Start VNC Remote Access For Guest Operating Systems
Эмуляция систем с помощью QEMU
libvirt.org
Using CGroups with libvirt and LXC/KVM guests in Fedora 12
Работа с виртуальными машинами KVM. Лимитирование ресурсов виртуальной машины
Лимит потребления процессора с иммунитетом к перезагрузке VDSа. KVM Mhz limit. KVM CPU limit
- good reference
- tips and tricks
[1]

KVM networking

Network management architecture
Network XML format

TODO

[root@kvm ~]# cd /var/lib/libvirt/images/

[root@kvm images]# ls

kvm01.img  kvm02.img  kvm03-clone.img  kvm03.img  lost+found

[root@kvm images]# fdisk -lu kvm03-clone.img 

You must set cylinders.

You can do this from the extra functions menu.

Disk kvm03-clone.img: 0 MB, 0 bytes

255 heads, 63 sectors/track, 0 cylinders, total 0 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x0007c171

          Device Boot      Start         End      Blocks   Id  System

kvm03-clone.img1   *        2048     1026047      512000   83  Linux

Partition 1 does not end on cylinder boundary.

kvm03-clone.img2         1026048    16777215     7875584   8e  Linux LVM

Partition 2 has different physical/logical endings:

     phys=(1023, 254, 63) logical=(1044, 85, 1)

[root@kvm images]# mount -o loop,offset=$[2048*512] kvm03-clone.img /mnt/disk/

[root@kvm images]# ls /mnt/disk/

config-2.6.32-71.el6.x86_64  initramfs-2.6.32-71.el6.x86_64.img  System.map-2.6.32-71.el6.x86_64

efi                          lost+found                          vmlinuz-2.6.32-71.el6.x86_64

grub                         symvers-2.6.32-71.el6.x86_64.gz

#这是虚拟机/boot的内容

[root@kvm images]# umount /mnt/disk/

[root@kvm images]# mount -o loop,offset=$[1026048*512] kvm03-clone.img /mnt/disk/        

mount: unknown filesystem type 'LVM2_member'

[root@kvm images]# losetup -f -o $[1026048*512] kvm03-clone.img 

[root@kvm images]# losetup -a

/dev/loop0: [fd02]:15 (/var/lib/libvirt/images/kvm03-clone.img), offset 525336576

[root@kvm images]# lvm pvscan

PV /dev/cciss/c0d1p5   VG vg_kvm1    lvm2 [68.33 GiB / 2.52 GiB free]

PV /dev/cciss/c0d0p2   VG vg_kvm     lvm2 [67.84 GiB / 0    free]

PV /dev/loop0          VG VolGroup   lvm2 [7.51 GiB / 0    free]

Total: 3 [143.68 GiB] / in use: 3 [143.68 GiB] / in no VG: 0 [0   ]

[root@kvm images]# ls /dev/mapper/

control  vg_kvm1-lv_date  vg_kvm1-lv_test  vg_kvm-lv_home  vg_kvm-lv_root  vg_kvm-lv_swap

[root@kvm images]# lvm vgchange -ay

2 logical volume(s) in volume group "vg_kvm1" now active

3 logical volume(s) in volume group "vg_kvm" now active

2 logical volume(s) in volume group "VolGroup" now active

[root@kvm images]# ls /dev/mapper/

control          vg_kvm1-lv_test  vg_kvm-lv_root  VolGroup-lv_root

vg_kvm1-lv_date  vg_kvm-lv_home   vg_kvm-lv_swap  VolGroup-lv_swap

[root@kvm images]# mount /dev/mapper/VolGroup-lv_root /mnt/disk/

[root@kvm images]# ls /mnt/disk/

bin   cgroup  dev  home  lib64       media  opt   root  selinux  sys  usr

boot  date    etc  lib   lost+found  mnt    proc  sbin  srv      tmp  var

然后就是卸载工作：

[root@kvm images]# umount /mnt/disk/

[root@kvm images]# lvm vgchange -an

Can't deactivate volume group "vg_kvm1" with 2 open logical volume(s)

Can't deactivate volume group "vg_kvm" with 3 open logical volume(s)

0 logical volume(s) in volume group "VolGroup" now active

[root@kvm images]# losetup -a

/dev/loop0: [fd02]:15 (/var/lib/libvirt/images/kvm03-clone.img), offset 525336576

[root@kvm images]# losetup -d /dev/loop0
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