Virtualization With KVM On Ubuntu 8.10

Version 1.0
Author: Falko Timme <ft [at] falkotimme [dot] com>
Last edited 12/10/2008

This guide explains how you can install and use KVM for creating and running virtual machines on an Ubuntu 8.10 server. I will show how to create image-based virtual machines and also virtual machines that use a logical volume (LVM). KVM is short for Kernel-based Virtual Machine and makes use of hardware virtualization, i.e., you need a CPU that supports hardware virtualization, e.g. Intel VT or AMD-V.

I do not issue any guarantee that this will work for you!

1 Preliminary Note

I'm using a machine with the hostname server1.example.com and the IP address 192.168.0.100 here as my KVM host.

Because we will run all the steps from this tutorial with root privileges, we can either prepend all commands in this tutorial with the string sudo, or we become root right now by typing

sudo su

2 Installing KVM And vmbuilder

First check if your CPU supports hardware virtualization - if this is the case, the command

egrep '(vmx|svm)' --color=always /proc/cpuinfo

should display something, e.g. like this:

root@server1:~# egrep '(vmx|svm)' --color=always /proc/cpuinfo
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext
 fxsr_opt rdtscp lm 3dnowext 3dnow rep_good nopl pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext
 fxsr_opt rdtscp lm 3dnowext 3dnow rep_good nopl pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch
root@server1:~#

If nothing is displayed, then your processor doesn't support hardware virtualization, and you must stop here.

To install KVM and vmbuilder (a script to create Ubuntu-based virtual machines), we run

apt-get install ubuntu-virt-server python-vm-builder

Afterwards we must add the user as which we're currently logged in (root) to the group libvirtd:

adduser `id -un` libvirtd

You need to log out and log back in for the new group membership to take effect.

To check if KVM has successfully been installed, run

virsh -c qemu:///system list

It should display something like this:

root@server1:~# virsh -c qemu:///system list
Connecting to uri: qemu:///system
 Id Name                 State
----------------------------------

root@server1:~#

If it displays an error instead, then something went wrong.

Next we need to set up a network bridge on our server so that our virtual machines can be accessed from other hosts as if they were physical systems in the network.

To do this, we install the package bridge-utils...

apt-get install bridge-utils

... and configure a bridge. Open /etc/network/interfaces:

vi /etc/network/interfaces

Before the modification, my file looks as follows:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
        address 192.168.0.100
        netmask 255.255.255.0
        network 192.168.0.0
        broadcast 192.168.0.255
        gateway 192.168.0.1

I change it so that it looks like this:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet manual

auto br0
iface br0 inet static
        address 192.168.0.100
        network 192.168.0.0
        netmask 255.255.255.0
        broadcast 192.168.0.255
        gateway 192.168.0.1
        bridge_ports eth0
        bridge_fd 9
        bridge_hello 2
        bridge_maxage 12
        bridge_stp off

(Make sure you use the correct settings for your network!)

Restart the network...

/etc/init.d/networking restart

... and run

ifconfig

It should now show the network bridge (br0):

root@server1:~# ifconfig
br0       Link encap:Ethernet  HWaddr 00:1e:90:f3:f0:02
          inet addr:192.168.0.100  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::21e:90ff:fef3:f002/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:23 errors:0 dropped:0 overruns:0 frame:0
          TX packets:24 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1580 (1.5 KB)  TX bytes:2356 (2.3 KB)

eth0      Link encap:Ethernet  HWaddr 00:1e:90:f3:f0:02
          inet6 addr: fe80::21e:90ff:fef3:f002/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:13539 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7684 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:19476849 (19.4 MB)  TX bytes:647692 (647.6 KB)
          Interrupt:251 Base address:0xe000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

vnet0     Link encap:Ethernet  HWaddr 3e:7c:6f:ab:0e:8c
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          inet6 addr: fe80::3c7c:6fff:feab:e8c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 B)  TX bytes:468 (468.0 B)

root@server1:~#