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Hypervisor

A hypervisor is a software or firmware layer that creates, runs, and manages virtual machines by abstracting and allocating physical hardware resources.

What is a hypervisor?

A hypervisor is the core component of virtualization that allows multiple virtual machines (VMs) to run on a single physical system. It sits between the hardware and the virtual machines, managing CPU, memory, storage, and network resources while keeping each VM isolated. Without a hypervisor, virtualization at scale would not be possible.

Why hypervisors matter

Hypervisors are critical because they:

  • Enable efficient server consolidation
  • Provide workload isolation and stability
  • Support rapid provisioning and scaling
  • Form the foundation of private and public cloud platforms
  • Allow multiple operating systems to run on the same hardware

They are a cornerstone of modern data centers.

Types of hypervisors

Hypervisors are commonly classified into two types:

Type 1 (Bare-metal hypervisors)

  • Run directly on the hardware
  • Higher performance and security
  • Used in data centers and production environments

Type 2 (Hosted hypervisors)

  • Run on top of a host operating system
  • Easier to use but less efficient
  • Common for development and testing

Hypervisor and security

From a security perspective:

  • Hypervisors provide strong isolation between VMs
  • A compromised hypervisor can expose all hosted workloads
  • Management interfaces are high-value attack targets
  • Patching and access control are critical

Hypervisor security is central to cloud and virtualization trust models.

Hypervisor vs operating system

  • Operating system: manages applications for a single environment
  • Hypervisor: manages multiple operating systems as guests

Hypervisors focus on resource allocation and isolation, not end-user functionality.

Hypervisors in cloud computing

Public and private cloud platforms rely on hypervisors to:

  • Isolate tenants in multi-tenant environments
  • Allocate resources dynamically
  • Enable live migration and high availability
  • Automate infrastructure management

Even container platforms ultimately run on hypervisors in many deployments.

Common hypervisor features

Typical hypervisor capabilities include:

  • VM lifecycle management (start, stop, snapshot)
  • Live migration
  • Resource scheduling and quotas
  • Virtual networking and storage
  • High availability and fault tolerance

Common misconceptions

  • "Hypervisors are just operating systems"
  • "Containers replace hypervisors"
  • "Hypervisors don't need hardening"
  • "Cloud providers don't use hypervisors"