What is a virtual machine

Virtual machine refers to hardware virtualization, which is usually used to provide a virtual environment to meet the needs of software. Virtual machines have the advantages of running multiple guest systems in parallel and improving hardware utilization efficiency.

Virtual machine

Virtual machine (VM) is a classic concept of hardware virtualization, usually used to provide a virtual environment to meet the needs of Software Requirements.

A VM is a virtual machine with its own operating system that uses the hardware resources of the underlying host system. Each virtual machine is based on hypervisor software (also known as a virtual machine monitor VMM). The hypervisor runs as an application on the host operating system (managed hypervisor) or resides directly on the hardware of the physical machine (bare metal hypervisor) and manages the hardware resources provided by the host system.

Hypervisor software creates an abstraction layer between physical hardware and virtual machines. Each VM is isolated from the host system and other guest systems in its own virtual environment, which is called encapsulation. Processes in a virtual machine do not affect the host or other VMs on the same hardware.

The actual use of virtual machines

In hardware virtualization, physical system resources can be distributed among multiple virtual systems, each guest system (including the one running in it) All programs) are separated from the underlying hardware.

In fact, for security reasons, virtual machines are mainly used to isolate certain processes and applications. Compared to other virtualization concepts, virtual machines provide powerful encapsulation capabilities and can serve as the basis for hosting products where multiple customer servers run on a common hardware platform.

The provision of virtual machines is the basis for shared hosting and VPS (Virtual Private Server) setups. Because each virtual machine system runs in an isolated operating environment, processes encapsulated in a VM do not affect the host system or other systems on the same physical computer.

In business environments, virtual machines are used to reduce the cost of operating and maintaining IT infrastructure. Companies often run extensive IT infrastructure that sits idle for much of the day, and virtual machines can significantly reduce this waste. Rather than giving each application area of ​​the business IT department its own physical machine, more and more companies are running mail, database, file or application servers in isolated virtual environments on the same powerful hardware platform. .

Another application area of ​​virtual environments is software development. Programmers who develop applications for different system architectures often use virtual machines for software testing. Many hypervisor products allow parallel operation of different operating systems or system versions. Create, clone and delete virtual machines in physical hard drive space with the push of a button without leaving any data behind. Additionally, due to encapsulation, errant processes in the virtual machine have no impact on the underlying system.

For domestic users, they like to use virtual machines to open more games, install some high-risk programs, and download seeds.

Advantages of virtual machines

1. Run multiple guest systems in parallel: Hypervisor-based virtualization can run multiple operating systems in parallel on the same hardware basis. Many hypervisors can bridge incompatibilities between different system architectures.

2. Improve hardware utilization by consolidating hardware: By running multiple virtual machines on a physical computer, hardware resources can be better utilized.

3. IT resource maintenance and management savings: Virtual machines offer huge savings potential in providing IT resources. Switching to a powerful hardware platform for various virtual systems can reduce maintenance and management costs because the corresponding tasks can be centralized.

Disadvantages of virtual machines

1. Hypervisor (and guest system) overhead: Virtual machines are less efficient than physical machines because some of the available resources are used for operational management Program software.

2. In terms of shared hardware: Power consumption spikes often cause bottlenecks: Since all virtual machines on the host system share the same hardware resources, performance spikes may cause bottlenecks.

3. Hypervisor as a single point of failure: If a hacker or malware attack targets the virtualization software, all guest systems managed by the hypervisor may be affected.

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