Virtualization Technology
Virtualization creates virtual versions of physical resources — servers, storage, networks, and operating systems. It is the foundational technology enabling cloud computing by maximising hardware utilisation and providing isolation between workloads.
Types of Virtualization
Server virtualization: multiple virtual machines on one physical server. Storage virtualization: pooling physical storage into logical units. Network virtualization: creating virtual networks independent of physical hardware (SDN, VLANs). Desktop virtualization: running desktop environments on central servers (VDI).
Hypervisors
Type 1 (bare-metal): runs directly on hardware (VMware ESXi, Microsoft Hyper-V, KVM, Xen). Better performance and security for production workloads. Type 2 (hosted): runs on top of a host OS (VirtualBox, VMware Workstation). Easier to set up, used for development and testing.
Virtual Machines
A VM is a software emulation of a physical computer with its own OS, CPU, memory, storage, and network interface. VMs provide strong isolation between workloads. Snapshots capture VM state for backup/rollback. Live migration moves running VMs between physical hosts without downtime.
Containers
Containers package applications with their dependencies in isolated user-space environments sharing the host OS kernel. Much lighter than VMs (MBs vs GBs, seconds vs minutes to start). Docker is the standard container platform. Containers are ideal for microservices, CI/CD, and consistent development environments.
Docker
Docker uses Dockerfiles to build images, Docker Hub to share images, and Docker Compose to define multi-container applications. Key concepts: images (read-only templates), containers (running instances), volumes (persistent data), and networks (container communication).
Container Orchestration
Kubernetes (K8s) manages containerised applications at scale. Features: automated deployment, scaling, load balancing, self-healing, rolling updates, and service discovery. Kubernetes is the industry standard for container orchestration in production environments.
Summary
Virtualization — from hypervisors and VMs to containers and Kubernetes — enables efficient resource utilisation, isolation, portability, and scalability that underpin cloud computing infrastructure.