🖥️Virtual Machines

NEW

Also known as: VM, Guest OS, VMs

A software-emulated computer that runs an operating system and applications isolated on shared physical hardware.

DESCRIPTION

Virtual machines abstract physical hardware via a hypervisor, enabling multiple isolated operating systems on one host. Type 1 hypervisors run on bare metal, while Type 2 run atop a host OS. VMs enable consolidation, isolation, snapshots, and live migration in clouds and data centers. Compared to containers, VMs provide stronger isolation but higher overhead. They remain foundational for IaaS, legacy workloads, and heterogeneous OS support.

ALTERNATIVE DEFINITIONS

VMware

A virtual machine (VM) is a software computer that, like a physical computer, runs an operating system and applications.

Defines VM as equivalent to physical computers in function.

Source

Oracle VirtualBox

A virtual machine is the software emulation of a computer system.

Emphasizes emulation of a full computer system.

Source

RELATED TERMS

Virtualization Hypervisor Bare Metal KVM VMware ESXi Materialized View Cloud Computing vCPU Paravirtualization Kubernetes VM Image Live Migration Infrastructure-as-a-Service

COMPETING TERMS

Containers

KNOWLEDGE AREAS

Infrastructure Cloud Software Engineering

TARGET AUDIENCE

Cloud Architect DevOps Engineer Software Developer Data Engineer Chief Technology Officer IT Manager Security Architect Cybersecurity Engineer

EXTERNAL SOURCES

• Wikipedia - Virtual machine
• Microsoft Azure - Azure virtual machines overview
• KVM - Linux KVM hypervisor project

TOP QUESTIONS

When should I prefer Virtual Machines over containers?

Choose VMs for strong isolation, different OS kernels, or legacy workloads. Containers fit lightweight, multi-tenant microservices sharing the host kernel.

Category: Requirements

What is the difference between Type 1 and Type 2 hypervisors?

Type 1 runs directly on hardware (bare metal) for performance; Type 2 runs atop a host OS for convenience and desktop scenarios.

Category: Basics

How do snapshots help in VMs?

Snapshots capture VM state for rollback and cloning. They aid testing, patching, and disaster recovery but can impact performance if overused.

Category: BestPractices

What are common performance considerations for VMs?

Right-size vCPU/RAM, optimize storage IOPS, use virtio drivers, and avoid overcommitment in latency-sensitive applications.

Category: Performance

How do VMs support hybrid cloud strategies?

Workloads packaged as VMs can migrate across on-prem and cloud IaaS via compatible hypervisors and images, aiding portability.

Category: Application

Do VMs provide security isolation?

Yes, hardware-assisted virtualization isolates guests, but shared host risks remain. Apply hardening and patch hypervisors regularly.

Category: Security

Can I run containers inside VMs?

Yes, many production setups run containers on VMs for layered isolation and consistent infrastructure management.

Category: Application

How does live migration work for VMs?

Memory and device state are transferred to another host while the VM runs, minimizing downtime during maintenance.

Category: Example

What images and templates are used with VMs?

Golden images or marketplace images provide base OS configurations. Packer or cloud images can automate image creation.

Category: BestPractices