351.1 Virtualization Concepts and Theory (weight: 6)

Tech Tutorial: 351.1 Virtualization Concepts and Theory (weight: 6) #

Introduction #

In today’s IT landscape, virtualization is a critical technology that allows multiple virtual machines (VMs) to run on a single physical server, leading to better resource utilization and flexibility. Understanding virtualization is imperative for system administrators, especially when preparing for Linux certification exams, such as those offered by the Linux Professional Institute (LPI). This tutorial aims to delve into the core virtualization concepts and theories, explaining their practical implementations and configurations.

Key Knowledge Areas: #

  • Types of Virtualization
  • Hypervisors
  • Virtualization vs Containerization
  • Benefits and limitations of virtualization

Utilities: #

  • KVM
  • QEMU
  • libvirt

Step-by-Step Guide #

1. Understanding Types of Virtualization #

a. Full Virtualization #

Using a hypervisor, such as KVM (Kernel-based Virtual Machine), full virtualization simulates enough hardware to allow an unmodified “guest” OS to be run in isolation.

# Install KVM
sudo apt-get install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils

b. Paravirtualization #

In paravirtualization, the guest OS is aware of the hypervisor and works with it directly for better performance. Xen is a common example.

c. OS-level Virtualization #

This involves containerization where, unlike virtual machines, containers share the host OS kernel. Docker is a popular example.

2. Hypervisors #

a. Type 1 (Bare Metal) #

These hypervisors run directly on the hardware. Example: Xen, KVM.

# Example: Installing Xen Hypervisor
sudo apt-get install xen-hypervisor-amd64

b. Type 2 (Hosted) #

These hypervisors run on a conventional operating system. Example: VMware Workstation, Oracle VM VirtualBox.

# Example: Installing VirtualBox on Ubuntu
sudo apt-get install virtualbox

3. Virtualization vs Containerization #

Understanding the difference between virtualization and containerization is crucial:

  • Virtualization allows multiple OS environments to coexist on the same hardware, completely isolated from each other.
  • Containerization shares the host OS kernel, and separates applications at the process level.

4. Benefits and Limitations of Virtualization #

Benefits #

  • Isolation
  • Utilization
  • Scalability

Limitations #

  • Overhead
  • Cost
  • Complexity

5. Practical Implementation Using KVM, QEMU, and libvirt #

a. Setting up KVM #

Check if your CPU supports hardware virtualization:

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

Install necessary packages:

sudo apt-get install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virt-manager

b. Creating a Virtual Machine with QEMU #

Create a disk image:

qemu-img create -f qcow2 ubuntu-server.qcow2 20G

Install an OS from an ISO file:

qemu-system-x86_64 -hda ubuntu-server.qcow2 -cdrom ubuntu-20.04.1-live-server-amd64.iso -m 2048 -boot d

c. Managing Virtual Machines with libvirt #

Install libvirt and tools:

sudo apt-get install libvirt-daemon-system libvirt-clients

Start and enable libvirt:

sudo systemctl start libvirtd
sudo systemctl enable libvirtd

List all virtual networks:

virsh net-list --all

Conclusion #

This guide has introduced the fundamental aspects of virtualization, diving into types of virtualization, understanding hypervisors, and distinguishing between virtualization and containerization. With practical examples using KVM, QEMU, and libvirt, you should now have a basic understanding of setting up and managing virtual environments. Virtualization is a vast field, and continuous learning and experimentation are key to mastering it.