Chapter 4: Virtualization and Cloud Computing

Cloud Computing

A model for delivering computing services (servers, storage, databases, networking, software, analytics, intelligence) over the Internet ("the cloud"), offering elasticity, scalability, and on-demand access to resources.

Public Cloud

A cloud deployment model where computing services are delivered by a third-party provider over the public internet and are available to anyone who wants to use or purchase them.

Private Cloud

A cloud deployment model where computing services are offered either over the internet or a private internal network and are used exclusively by a single organization.

Hybrid Cloud

A cloud deployment model that combines a public cloud and a private cloud, allowing data and applications to be shared between them.

Community Cloud

A collaborative cloud infrastructure that is shared by several organizations with common concerns (e.g., security, compliance, jurisdiction).

Infrastructure as a Service (IaaS)

A cloud service model where a third-party provider hosts hardware, software, servers, storage, and other infrastructure components, and the client manages the operating systems, applications, and data.

Software as a Service (SaaS)

A cloud service model where a third-party provider hosts and manages the application and its underlying infrastructure, making the software available to users over the internet.

Platform as a Service (PaaS)

A cloud service model that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app.

Metered Utilization

A billing model in cloud computing where users pay only for the resources they actually consume, such as data transfer (ingress/egress), storage, or compute time.

Non-metered Utilization

A billing model where users pay a fixed price for a block of resources, regardless of the actual usage, often with no additional costs for data transfer.

Elasticity (Cloud Computing)

The ability of a cloud system to rapidly scale computing resources (up or down) to meet fluctuating demands without manual intervention.

Availability (Cloud Computing)

The measure of how consistently a system or service is accessible and operational, often enhanced in the cloud through redundancy and distributed infrastructure.

File Synchronization

The process of ensuring that files in two or more locations are identical, often used in cloud computing to duplicate information across multiple cloud locations for redundancy and access.

Multitenancy

A software architecture where a single instance of an application serves multiple customers, or "tenants," who are logically isolated from each other

Virtualization

The process of creating a virtual version of something, such as an operating system, server, storage device, or network resources. It allows one physical computer to run multiple operating systems and applications independently.

Sandbox

An isolated testing environment that separates untested code or programs from the production environment, preventing any potential harm or disruption to the real system.

Host-based virtualization

A virtualization model where the hypervisor runs as an application on top of an existing operating system (the host OS), which then hosts guest operating systems.

Hypervisor (Virtual Machine Manager)

Software that creates and runs virtual machines (VMs). It manages the virtual platform and guest operating systems, allocating resources like CPU, memory, and network.

Type 1 Hypervisor (Bare Metal)

A hypervisor that runs directly on the host computer's hardware, without a separate operating system beneath it.

Type 2 Hypervisor (Hosted)

A Type 2 hypervisor runs within an existing operating system and relies on the host OS to manage hardware resources

Guest Operating System (Guest OS)

An operating system installed and running within a virtual machine on a host system.

VM escaping

A security vulnerability where malicious code running in a virtual machine breaks out of its isolated environment and interacts with the hypervisor or other virtual machines on the same host.

Rogue Virtual Machine

An unauthorized or malicious virtual machine deployed on a system, often by attackers, to gain access or carry out nefarious activities.

Virtual Desktop Infrastructure (VDI)

A virtualization technology that hosts desktop operating systems and applications on a centralized server, allowing users to access them remotely from various client devices.

Desktop as a Service (DaaS)

A cloud-based service model where a third-party provider hosts the back-end VDI infrastructure, streaming virtual desktops to end-users over the internet.

Application Containerization

A form of virtualization that packages an application and all its dependencies (libraries, frameworks, configuration files) into a single, isolated unit called a container, which can run consistently across different computing environments.

Container Image

A lightweight, standalone, executable package of software that includes everything needed to run an application: code, runtime, system tools, system libraries, and settings.