What is a Hypervisor? Understanding Types, Benefits, and Their Role in Virtualization

Get to know hypervisors, their types and benefits in virtualization, and their use cases in server, desktop, and cloud environments with expert opinions.

Updated: 02 Feb, 25 by jean lou 15 Min

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What is a Hypervisor? Commonly called Virtual Machine Monitor, the hypervisor is a key technology that makes virtualization possible through multiple VMs - on a single physical hardware system. It has an important role, so it is like the mediator acting between hardware and virtual machines, being efficient in terms of resource allocation and isolation. 

In this article, the focus is on two types of hypervisors: Type 1 or bare-metal hypervisors, and Type 2 or hosted hypervisors. Their architectures and how they are really important in modern computing environments such as cloud computing, data centers, and software testing, are also going to be described. Indeed, understanding these hypervisors creates the very foundation of virtualization and its tremendous impact on IT infrastructure.

A hypervisor is software, firmware, or hardware that enables the formation and management of virtual machines, or VMs, on a single physical host system. It is a kind of virtual machine monitor (VMM). 

A hypervisor acts as an intermediate layer between the physical hardware and VMs by abstracting hardware resource portions, such as CPU, memory, storage, and network interfaces.

  • The importance of hypervisors is that they manage and allocate the hardware resources to multiple VMs while keeping them isolated and independent.
  • The services offered are to ensure that the operation of one VM does not interfere with those of others, thus providing a controlled and secure execution environment. 
  • The scheduling of CPU time for a specific VM is done by the hypervisor; it allocates memory according to the demand it obtains dynamically and virtualizes network access. 

If you want to know more about Linux virtual machines, Read this article: Linux Virtual Machine

Type 1 hypervisors (also go with bare-metal hypervisors) are hypervisors that run directly on the host hardware without having to go through an operating system. Such hypervisors talk directly to the physical resources such as CPU, memory, or storage in the creation and management of virtual machines (VMs). Direct access is the basis on which it operates with minimal operating overhead-which is what renders it highly efficacious, and reliable for virtualization at enterprise levels.

Advantages of Type 1 Hypervisors:

  • Better Performance: As there is no intermediary in the way such as OS, there is low latency currently.
  • Better Security: There is less attack surface, as there is not a general-purpose operating system, lowering vulnerabilities.
  • Higher Scalability: Very suitable to environments of much greater size, such as data centers and cloud infrastructure.
  • Better Resource Management: Well-optimized allocation and scheduling of resources, right from the hardware level.
  • Dependability: The dependability there is hardly any chance of damage to the system as there is no common host OS making it very suitable for mission-critical applications.

Some instances of widely applied Type 1 Hypervisor over many physical, enterprise, or even cloud environments include VMware ESXi, Microsoft Hyper-V, and Xen.

A hosted hypervisor or type 2 hypervisor executes above an already running operating system (i.e. host OS), thereby not interfacing directly with hardware. It is dependent on the host OS to manage hardware resources provisioning for the creation and execution of virtual machines. 

Typical use cases relate to desktop virtualization, software testing, and other types of provisioning for "non-enterprise" usage that essentially prioritizes functionality over performance.

Benefits of Type 2 Hypervisors:

  • Easy installation and setup: Because of installation above a host OS, Type 2 hypervisors can be installed as applications and offer services to even non-experts.
  • Interface: Typical well-designed interfaces, often graphical with GUI, ease the creation and management of VMs for the everyday user and developer.
  • Use of Host OS Resources: Use of host hardware drivers and resources, which ensures that it works with a range of hardware without additional configuration.
  • Great for Development and Testing: It makes it easy for users to create VM testbeds for testing alternate operating systems, applications, and configurations; no dedicated hardware is needed.
  • Cost-Effective for Personal Use: Either free or at lower prices than those enterprise-grade Type 1 hypervisors, making them most appropriate for small-scale and personal projects.
  • Resource allocation is flexible. The host operating system can dynamically distribute resources between the VMs, enabling the user to fine-tune performance according to current workloads.
  • Portability: Virtual machines built by Type 2 hypervisors can easily transfer to different systems running the same hypervisor software.

Disadvantages of Hypervisors of Type 2:

Compared to Type 1 hypervisors, Type 2 supplies all the mentioned advantages but comes with a few disadvantages:

  • Lesser Performance: The overhead caused by the dependent host OS reduces performance during processing in most cases, especially in resource-intensive applications.
  • Higher vulnerability: If the host OS has any security vulnerabilities they would directly impact the virtual machines.
  • Less number of users: Most suitable for single-user use or small deployments rather than large organizations deploying it.

If you want to know more about the most common cyber security threats, Read this article: The Most Common Cyber Security Threats and How to Mitigate Them.

VMware Workstation, Oracle VM VirtualBox, and Parallels Desktop are the most popular examples of Type 2 hypervisors available now and widely used in both personal and professional domains for different purposes of virtualization.

Hypervisor architecture refers to the real-time interactions between the host system components and the virtual machines that run on them. This hypervisor layer abstracts CPU, memory, storage, and network interfaces as resources into isolated environments in which multiple VMs can run. Each VM, in turn, runs as an independent system, with virtualized hardware and operating system. 

Thus, several workloads can operate in parallel in a single physical machine. Either directly with the hardware (Type 1) or via the host operating system (Type 2), this interaction occurs depending on the hypervisor type.

An imaginary VMM gives this view of virtualized hardware where each free VM is allocated and managed resources efficiently. The approach perceives each hardware component virtually. 

For example, it allocates portions of CPU cycles to the host, RAM, and storage according to the latter's needs for each virtual machine. Resource isolation means that one operation contaminates another virtual machine. 

The hypervisor allows VMs to self-communicate through a host system by converting virtual requests into actions on physical hardware. Sophisticated scheduling and allocation algorithms apply, optimizing performance for purposes such as live migration and high availability. 

The architecture is structured in the following way: 

It begins with a host system at the base, emerging with the hypervisor layer, then next showcasing several VMs that run on top and appear as a whole system unto themselves sharing with other physical ports.

For more information about how to check open ports in Linux, read this article: How to Check Open Ports in Linux

Hypervisor vs. Virtual Machine

A hypervisor is defined as a software or hardware layer for virtualization. It creates and manages virtual machines (VMs). A virtual machine virtually emulates a computing environment created on top of the hypervisor and runs applications as if they were running on a physical system.

Definition:

  • Hypervisor: The foundation on which virtualization is built to create and administer VMs.
  • Virtual Machine: The isolated virtual environment created by a hypervisor that runs an application or operating system.

Function:

  • Hypervisor: Handlers, utilized to intermediate resources between host and multiple VMs.
  • Virtual Machine: It consumes resources from this hypervisor and functions by looking exactly like an entirely independent system.

Dependence:

  • Hypervisor: Independent functioning and qualified for virtualization.
  • Virtual Machine: Entirely dependent on hypervisor for the allocation of resources to work and execution.

Role in Virtualization:

  • Hypervisor: Enable virtualization by abstracting from physical hardware and presenting different environments.
  • Virtual Machine: The application example of virtualization, for instance, runs applications and operating systems.

Resource Management:

  • Hypervisor: Manages how physical resources, such as CPU, memory, and storage, are shared among VMs.
  • Virtual Machine: Consumed and operationally constrained by the hypervisor-defined resources allocated.
  • Reuse of resources: Hypervisors allow several VMs to operate on a single physical machine so that it can optimize hardware resource use. Hypervisors virtualize the components such as CPU, memory, or storage thus maximizing utilization of the entire system.
  • Maintenance and Management Simplification: Hypervisors can achieve IT operations by centralization of multi-virtual machines, besides live migration and snapshot capability as well as backup processes in lower downtimes and thus improve reliability overall.
  • Isolation: Hypervisors create entirely isolated environments for each of their VMs so that the actions of a single VM do not affect any others. This makes hypervisor utilization much more secure.
  • Scalability: Hypervisors scale easily without requiring any further hardware addition; all that is required is increasing or decreasing the number of hosted virtual machines. Its facilitated flexibility is most applicable in any enterprise environment and cloud computing. 
  • Cuts in Hardware Expenses: Hypervisors reduce costs in hardware because they can reduce the number of physical machines into which several servers can be consolidated.  

Cloud computing platforms use hypervisors to provide virtualization technology, which facilitates the operation of services like Amazon EC2, Google Cloud VMs, and Microsoft Azure. 

Hypervisors create and manage virtual machines (VMs) for the hosting of multiple customers on the same physical servers while keeping user environments secure and isolated. This property is extremely important for the services provided in public clouds: multiple tenants share the same resources. 

Hypervisors abstract out the actual hardware, use dynamic allocation of resources such as CPU, memory, and storage, and change the power of computing in scaling according to the needs of the customer, hence resulting in very flexible infrastructure solutions, cost-effective.

Hypervisors ensure strong resource management and workload isolation in virtualized cloud environments. Each VM will run independently and is unaffected by any interruption or security breach from a neighboring VM. 

Thus, performance can be assured along with the security of data even in multi-tenant scenarios. They even cater to other state-of-the-art cloud features like auto-scaling, live migration of workloads, and high availability, the mainstay of modern and resilient cloud architecture. 

  • Cloud Hosting: Hypervisors are also critical for cloud hosting because they are used to create and maintain virtualized environments whereby different users can access them. Hypervisors ensure efficient uses of resources safe isolation of workloads and scalability forming the backbone of public, private, and hybrid cloud solutions.
  • Server Virtualization: Hypervisors are extensively used within both public and private instances to virtualize servers such that several servers get consolidated into VMs that operate on a single physical machine thus reducing hardware requirements, improving resource utilization, and simplifying management, making it ideal for enterprise IT environments.
  • Desktop virtualization: A type 2 hypervisor enables desktop virtualization, thus allowing multiple operating systems to be run on a single device by a user.  

The right hypervisor is dependent upon the user requirements and the specific use case. For instance, type-2 hypervisors work well for home or personal applications, especially where the use is merely testing an application, running different operating systems, or tinkering with virtual environments. 

These hosted hypervisors, like VMware Workstation or Oracle VM VirtualBox, are easier to interact with, install, and available for use over another operating system. They are best in mini-environments where easy setup and compatibility take precedence over performance.

However, for very serious environments where stringent performance and scalability are mandatory, enterprise solution-oriented Type 1 hypervisors are available, like VMware ESXi or Microsoft Hyper-V. These are bare-metal hypervisors that run above and below operating system ends, hence providing a native experience. 

This allows these specialized OSs to be matched closely with actual hardware and hence maximize performance, resource efficiency, and security. They are generally Type 1 hypervisors considering the data centers, cloud computing, and the virtualization infrastructure need very high reliability and scalability.

Among these options, several factors can be evaluated to come up with a choice: performance, scalability, ease of use, and cost. Type 2 hypervisors can well suit the use on a smaller scale, even individuals, because they are quite simple in design yet flexible in deployment. 

Meanwhile, Type 1 hypervisors are appropriate in an enterprise setting, requiring high availability with complex features such as live migration and disaster recovery. 

Conclusions

The virtualization part of hypervisors is a critical ingredient in resource efficiency, security of workloads, and scalability on a server (or cloud) basis. Their value to the data center and cloud-making platforms makes them a lifeblood of IT infrastructure in their most fundamental form. 

MonoVM hosting, for example, offers hypervisor-powered solutions through which clients can obtain secure and scalable virtual environments that ideally meet the dynamic needs of their businesses, confidently and reliably. The knowledge of hypervisors and the benefits derived from these have empowered many organizations to make smart decisions concerning their operations and embrace the full implications of virtualization.

The hypervisor is software or hardware that enables virtualization by creating and managing virtual machines on a host physical system.

There are two types: Type 1 (bare-metal) hypervisors run directly on hardware, whereas Type 2 (hosted) hypervisors run on top of an existing operating system.

A hypervisor creates an isolated virtual, enabling a cloud provider to allocate and manage resources specifically, and efficiently among multiple users.

For personal use, Type 2 hypervisors due to simplified installation and compatibility with the computer operating system, are VMware Workstation and VirtualBox.