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Virtualization & Cloud Computing

Study Guide

Virtualization and cloud computing make up 11% of Core 1. You need to understand virtual machines, hypervisors (Type 1 vs Type 2), resource requirements, and cloud service models (IaaS, PaaS, SaaS) and deployment models (public, private, hybrid).

1Virtualization Concepts

Virtualization lets you run multiple operating systems on one physical machine using virtual machines (VMs). A VM is a software-based computer with its own virtual CPU, RAM, storage, and network. Hypervisors manage VMs and allocate physical resources. Snapshots capture a VM's state so you can revert changes.

Examples:

•A Type 1 hypervisor (bare-metal) runs directly on hardware — VMware ESXi, Microsoft Hyper-V
•A Type 2 hypervisor (hosted) runs on top of an OS — VirtualBox, VMware Workstation
•Snapshots let you save a VM state before making changes and roll back if something breaks
2Cloud Computing Models

Cloud computing delivers resources over the internet. The three main service models are IaaS (you manage OS and apps), PaaS (you manage only apps), and SaaS (you only use the application). Deployment models include public (shared infrastructure), private (dedicated to one organization), hybrid (mix of both), and community (shared among organizations with common goals).

Examples:

•IaaS: Amazon EC2, Azure VMs — you manage the OS, middleware, and apps
•PaaS: Google App Engine, Azure App Service — you deploy code, the provider manages everything else
•SaaS: Gmail, Microsoft 365, Salesforce — you just use the application
3Virtualization Requirements

Each VM requires allocated CPU cores, RAM, storage, and network connections. Resources can be overcommitted (assigning more virtual resources than physically available) but this can cause performance issues. A hypervisor manages resource allocation among VMs. Templates and golden images speed up VM deployment.

Examples:

•If a host has 32GB RAM and you allocate 8GB to each VM, you can run a maximum of 4 VMs at full allocation
•Overcommitting RAM means assigning more total virtual RAM than physical RAM — works if VMs don't all use their full allocation simultaneously
•A VM template is a pre-configured image used to quickly deploy new VMs with consistent settings
Test-Taking Tips
Type 1 hypervisors run directly on hardware (faster, used in data centers). Type 2 run on top of an OS (slower, used on desktops).
IaaS = you manage everything above hardware. PaaS = you manage apps. SaaS = you just use it.
Snapshots are not backups — they depend on the original VM disk and should not be used for long-term retention.
Cloud computing is an OpEx (operational expense) model — pay as you go, no upfront hardware cost.