Hypervisor vs Virtual Machine

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Introduction

Hypervisor technology is often overlooked in favor of the trendier concept of virtualization. However, you will not get absolute pleasure from using virtualization until you understand what a hypervisor is and how it works in a computing system.

Many articles and words have been written about the benefits of cloud computing and virtual servers. However, it is still worth throwing such thoughts out of your head because hypervisor technology can help in stimulating innovation in the world of cloud computing. We have compiled some great information regarding hypervisor vs virtual machine. Just have a look.

What is a hypervisor?

A hypervisor is a software that manages virtual machines and allows multiple virtual machines to run on a single physical server. Thus, we can say that this is a virtualization system. To provide VDS services with an operating system of the Linux / FreeBSD family, the KVM system (OpenStack) is used. In addition, the Windows operating system uses Microsoft\’s Hyper-V system.

A hypervisor decouples a computer\’s operating system and applications from the underlying physical hardware. Usually, it is software, although built-in hypervisors are also created, for example, for mobile devices.

The hypervisor is the driving force behind the concept of VPS and virtualization, allowing a physical host computer to manage multiple virtual machines as guest OSs, which in turn helps to make the most of computing resources such as memory, network bandwidth, and processor cycles.

History of hypervisors

In the late 1960s and up to the 1970s, most virtualization systems and hypervisors were seen on mainframes developed by IBM. They use them to formulate time-sharing processes for using a computer, test new operating systems and ideas for improving them, or learn new hardware concepts. Virtualization allowed programmers to deploy systems and troubleshoot without compromising the stability of the central production system, and it eliminated the need to deploy additional expensive systems.

In the mid-2000s, hypervisors reached a new level when UNIX, Linux, and other Unix-like operating systems used virtualization technologies.

Types of hypervisors

Most commonly, there are two types:

Type 1 hypervisors, sometimes referred to as \”stand-alone hypervisors,\” run directly on host hardware to manage hardware and manage guest virtual machines. Modern hypervisors of the first type include Xen, Oracle VM Server for SPARC, Oracle VM Server for x86, Microsoft Hyper-V, and VMware ESX / ESXi. By the way, all Windows VDS servers running on VSP. House are running under Hyper-V.

Type 2 hypervisors, sometimes referred to as \”host hypervisors,\” run on a regular OS just like other applications on the system. In this case, the guest OS runs as a process on the host, and the hypervisors separate the guest OS and the host OS. Examples of Type 2 hypervisors are VMware Workstation, VMware Player, VirtualBox, and Parallels Desktop for Mac.

Now, there are three leading major hypervisor developers: VMware, Microsoft, and Citrix Systems.

Hypervisor security issues

While hypervisors are considered more secure than containers due to many precautions, this does not mean that hypervisors have no security concerns at all. The hackers usually create viruses and harmful programs, which look like hypervisors. This process, known as \”hyperjacking\”, is difficult to detect because malware can intercept the operating system\’s actions (such as entering a password) without the need to protect against malware since this malware is already running under the OS.

Professionals in the virtualization world can endlessly debate whether it can detect a hypervisor-based rootkit. Several approaches have already been created on this topic. Some have introduced the concept of malware (SubVirt and Blue Pill), and others have demonstrated the Hooksafe anti-rootkit, which effectively protects the operating systems\’ rootkits without decreasing the machine\’s performance.

What is a virtual machine?

Gone are the days when companies everywhere built server rooms with their hardware. With the advent of virtual machines, millions of square meters of space have been freed up, and hundreds of thousands of outdated servers have become a heap of unnecessary metal. In addition, the second life began without a headache, without disastrous budgets, without sleepy nights of administrators who now and then change out-of-order equipment.

A convenient solution was found, without which practically no organization could do today. Therefore, as you understand, today, we will focus on virtual machines.

A virtual machine is an exact copy of a regular computer or server with any desired OS and a set of installed programs. It is impossible to touch it, but it is natural to feel it. You can work with a VM (this is how a virtual machine is abbreviated) as a physical server or a stationary computer. However, it is enough to connect, access the VM, special services are used, or a cloud service provider provides a console. The main thing is to have access to the network and an account with the appropriate authority.

On the other hand, a virtual machine is a program that emulates a real computer or server and runs in a separate window. It consists of a virtual hard disk, processor, memory, network and video cards, device controllers, and other elements. The beauty of the virtualized approach is the ability to control the resources of the machine yourself: you can increase or decrease the resources used on-demand and do it in a matter of seconds. In the case of a physical server, if, for example, you need to increase RAM, you will have to buy an additional line of memory, spend time and money on it.

Like any other program, a virtual machine consists of files stored on the disks of a physical server inside the file system of the hypervisor. Today, there are several options for hypervisors presented by various market players (VMware, Microsoft, Citrix, etc.). Therefore, each product has a different set and format of files. For example, a virtual machine can be represented as a file with the .vmdk or .vhdx extension. In addition, it stores in itself the OS, drivers, and related data.

Uses of Virtual Machines

To deploy two or more independent operating systems on a single physical device. For example, you have Windows 7 operating system installed on your computer, and you have installed Windows XP / 8/10 or Linux on the virtual machine;

For experimenting with software (for example, code designed to run on different operating systems) without compromising the stability of the computer;
To install and test various programs and utilities without taking up space on the main PC;
To run programs that is not supported by the central Operating system or to connect equipment incompatible with it. For example, use Windows programs on Mac or Linux;
For the safe launch of an application (program) that arouses mistrust or suspicion of viruses;
To emulate computer networks and complex environments without having to set up a virtual machine every time. You can save the settings and continue where you left off;
To create backups of the OS.

Virtual machine benefits

Virtual machines provide so many benefits during multitasking. Some of these are:

You can turn off the PC or go to another task while maintaining the current state of the machine. If you decide to continue working, the VM will boot in the state where it was at the time of shutdown.
You can take snapshots on a VM that allows you to roll back to previous configurations. It is helpful if a critical error occurred while testing unstable software. Compared to the central system, VMs are allocated less disk space, and rollback to an early state is faster.
The machine can be saved or duplicated as an isolated environment. It can be run later or copied to another PC. It also allows saving specific configurations.
You can quickly transfer Virtual machines along with all data from one PC to another. Portable software for a virtual machine stores information in one file (in a system image) on a physical computer. To transfer it is enough to move this file.
The VM does not occupy the place of permanent memory but operates with the allocated temporary memory. All actions are recorded in the form of a log, which is cleared at the end of each session.
To reconnect to another OS, you do not need to restart your computer.
One device can store several virtual machines with several operating systems in different states.

The difference between a VM and a physical server

If you illustrate the difference between a regular server and a virtual machine, it will look like the one shown in the picture. In the first case, when we are talking about a physical server, the operating system is installed on hardware using pre-installed physical components. However, in the second case, a hypervisor is installed on the server – a unique technology that creates an appropriate environment for deploying virtual machines. Please note that you can deploy many virtual machines on one such server isolated and independent from each other. Each VM consumes as many virtual resources (RAM, CPU, and processor) as specified during its creation or subsequent configuration.

Hypervisor vs Virtual Machine

Hypervisors are software that distributes hardware resource capacities among several operating systems, allowing them to launch simultaneously.

Hypervisors create copies (or clones) from one physical machine. Each \”clone\”, however, is visible to the user as a separate device. Thus, you can install a guest OS on each virtual machine that is not tied to the host computer.

The hypervisor separates the operating system running from each other so that each OS only uses the resources it has been allocated. The hypervisor can allow virtual machine operating systems to interact with one another if needed. Communications between operating systems can be made possible by sharing files and data exchange over a local network.

We have thus several virtual machines instead of just one physical machine. Each of them runs its software and independently from the others. Each virtual machine is a collection of files on the host disk. The hypervisor will cease to work if the physical server goes down, and all virtual machines will vanish.

The virtual machine uses Virtualization technology to create a virtual representation or cluster of computers or servers on the hardware basis of one physical computer. This hardware base is called a host. It has a CPU and RAM as well as drive space. In addition, you can install Specific software to diversify physical resource capacities and create multiple virtual machines that are independent of each other.

Virtualization, de facto, is an illusion that multiple autonomic computers exist, i.e., virtual machines or instances based on one physical device. A hypervisor creates this illusion.

The cost of maintaining virtual machines on a single server is very cost-effective. Because you can host them on multiple servers, you can currently rent resources from such a virtual VPS server at a very affordable price. Websites are hosted on such servers.

Reasons to adopt virtualization-using hypervisors

Firstly, the reason was to improve the hardware capabilities and power, which would now allow one machine to do more synchronized work. Second, increased cost control led to server consolidation; third, security and reliability played a significant role due to the improvement of hypervisor architecture. Last but not least, of course, the ability to run OS-dependent applications in different hardware or operating environments. In addition, in 2005, processor developers began to add hardware virtualization to their x86-based products.

Final verdict:

Programming is done for one operating system. These programs use these operating system features when they interact with devices and interfaces. Therefore, it is not possible to copy the program and then run it in another environment. Hypervisor virtualization lets you run two operating systems on one machine. It solves the problem that programs do not run on the current system.

Virtualization can be done in three ways: hardware, software, and container. Modern processors do not support software virtualization, but hardware virtualization offers many benefits over software virtualization. Containerization makes it easy to deploy a development environment quickly.

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