Lec 16: Introduction to Virtualization

Introduction to virtualization

Virtualization is the foundational technology behind cloud computing. It allows a single physical machine to present multiple independent virtual machines (VMs), so many users or workloads can run concurrently while each user feels they have their own system.

Analogy: a single wall power socket vs. an extension box with multiple outlets — the physical resource is one, virtualized into many accessible points.

Core concept

• One physical host can be partitioned into many virtual machines.
• Each VM is independent and can run its own guest operating system and applications.
• Virtualization hides the physical characteristics of resources (CPU, RAM, storage, network) from users.

How it works

• A hypervisor (virtual machine monitor) is the primary software layer that enables virtualization. It runs on the host server/hardware and creates VMs.
• The hypervisor allocates resources (CPU, RAM, storage, etc.) to each VM and enforces isolation between VMs.
• VMs can run different guest operating systems (Windows, Linux, macOS, etc.) on top of the host hardware without modifying the underlying physical machine.

Benefits

• Better utilization of compute resources (reduces idle CPU/RAM/storage).
• Lower physical hardware cost (multiple VMs per server).
• Improved fault tolerance and easier failover (VMs can be migrated or shifted).
• Reduced power and cooling needs (fewer physical machines).
• Increased agility and productivity — rapid provisioning of environments and OS-specific applications.

Modes of virtualization

• Full virtualization

  • The hypervisor completely simulates hardware.
  • The guest OS runs unmodified and is unaware it’s virtualized.
  • Good for compatibility with unmodified guest OSes.

• Paravirtualization

  • The guest OS is modified to cooperate directly with the hypervisor.
  • The guest is aware of virtualization and can achieve improved performance.

Practical / teaching points

• Use-case: instead of replacing a host OS to run a different OS, create a VM on top of the existing host and install the desired guest OS and applications there.
• Emphasis on isolation: each VM runs its own apps independently, with the hypervisor managing resource allocation and containment.

Main speaker / source

• Lecture 16 of an unnamed course (course lecturer/instructor).