Meeting: 25th November 2012 – Virtualisation 1

  • Topic: Virtualisation from the Ground Up
  • Host: Jon A

An introduction to virtualisation

What is Virtualisation?

  • Multiple instances of different operating systems running on the same piece of hardware.
  • Traditional environment – multitude of tin.
  • Virtual environment – minimal tin.
  • Power savings etc.

How does it work

  • Hardware virtualisation instruction set in CPU.
  • Hypervisor layer.
  • Shared Hardware resources.
  • Hard disk images.

Software Available?

  • Virtualbox (OSE) – Oracle.
  • VMWare
  • Xen – Citrix.
  • KVM – RedHat.
  • HyperV – Microsoft

Pre-Flight Checks – Hardware

We need to make sure our hardware is capable of virtualisation

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

0 = no hardware support

1 or more = hardware support available but may need to ensure switch is set in the bios

Pre-Flight Checks 2 – CPU

Install cpu-checker

apt-get install cpu-checker kvm-ok

Example output:

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

Pre-Flight Checks 3 – Kernel

Use a 64 bit kernel (if possible), To serve more than 2GB of RAM for your VMs, you must use a 64-bit kernel.

egrep -c ' lm ' /proc/cpuinfo 0 means no 64 bit

1 or more means it is

Now lets check we are running a 64 bit kernel

uname -m

if x86_64 is listed we’re golden!

Check your CPU is 64 bit capable


For this demonstration Ubuntu and KVM is used

Ubuntu 12.04 Server

User called virtdude was created on install

Ubuntu Installation

Basic server install OpenSSH server added after reboot conduct the usual update

sudo apt-get update sudo apt-get dist-upgrade KVM Installation

Lets install the needed packages:

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

  • libvirt-bin provides libvirtd which is the daemon for monitoring qemu and kvm instances using libvirt.
  • qemu-kvm is the backend hypervisor.
  • bridge-utils provides a bridge from your network to the virtual machines.
  • ubuntu-vm-builder powerful command line tool for building virtual machines, uses debootstrap.
  • KVM – User Privileges

Ensure user is a member of the libvirt group

sudo adduser `id -un` libvirtd Now is probably a good opportunity to reboot.

KVM – Lets connect

Now we have the environment built, the hardware is setup and the hypervisor is running

Lets connect to the hypervisor to test

virsh list

Example output:

Id Name State

No VM running but a successful connection to the hypervisor


Out of the box we get a NAT

eth0 = Ideal for testing/single host

We want a bridge onto physical LAN

br0 =


Virtualised machines are called guests

Lets make one

On the “management machine” install virt-manager for gui access

sudo apt-get install virt-manager

All eggs in one basket?

Single piece of tin multiple OS

Lets bring online a second host

Host 2

Eggs in 2 baskets?

Load balancing

  • Resilience
  • Shared storage
  • NFS Shared Storage

Lets install NFS on host 1

sudo apt-get install nfs-kernel-server

mkdir /export on host1

mkdir /import on both

cat <EOF»etc/exports

/export *(rw,no_root_squash)

EOF Lets reboot to get NFS running

We now need to add the storage in the GUI console


We should now be able to migrate a VM from one host to the other

Migration copies the memory footprint and configuration of the running guest from host to host, without dowtime (or at least very little).

As we’ve proved, shared storage is required for this to work, so that both hosts can see the same virtual hard disk file

Local NFS – The Bad news

  • NFS is great if you have a dedicated storage appliance
  • Most virtualisation environments utilise filers with multiple disk arrays presented over various protocols such as NFS/iSCSI/FCOE/etc NetApp, EMC, Sun, HP, etc.
  • We’re back to having one basket with a local NFS setup.

Clustered File Store

If storage must reside on the same hardware as the hypervisor, then we must make the storage available from all hypervisor hosts


storage hosted on all hypervisors and presented via NFS

Essentially raid volume over multiple hosts giving the required resilience


  • Removed the need for lots of physical hardware.
  • Thus saving power/money etc.
  • Provided resilient infrastructure.
  • Created our own personal cloud.

What Next?

  • oVirt – nice management tools
  • Expand the cloud.
  • Public/Private.
  • Openstack – Amazon EC2.
  • Ubuntu Tools – Juju/Charms.
  • World domination – 1 gazillion dollars.

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