Virtualization technology is not a particularly new term. There are many mature products, both open source and commercial.
Why do we need this technology? The answer is to combine or utilize resources in more detail.
Terms related to virtualization technologies
| The term | define | The sample |
|---|---|---|
| The operating system | Software used to allocate physical resources to applications | Windows Linux |
| application | Software that runs on an operating system | Chrome, QQ |
| The virtual machine | In hardware resource abstraction processing for software specific applications | |
| The client | The operating system running on the VM | Windows Linux |
| Hypervisor | An operating system specially designed for a virtual machine | ESXI, Workstation, Fusion |
| The host | The physical computer that provides resources for the hypervisor |
Under normal circumstances, our host can directly install Windows and other operating systems, the operating system to call the host resources, but if the host hardware resources are too much, only install an operating system how wasteful it. Therefore, the hypervisors technology is derived, and different operating systems can be installed on a single host. The hypervisor layer is responsible for allocating hardware resources to different operating systems. And the upper-layer system is very convenient to migrate, because the hypervisor layer is isolated, the upper-layer operating system is just a bunch of encapsulated files, not affected by the physical hardware.
VSphere virtualization
VSphere is a virtualization product produced by VM company, powerful, simple to operate, but charged.
The ESXi Hypervisor technology is used to isolate the underlying physical resources, such as CPUS, RAM, disks, and networks, from the Windows operating system. ESXi allocates physical resources to VMS and then installs the required OPERATING system (OS) on the VMS.
Physical architecture and virtual architecture:
Through the change of architecture, the virtual machine can share physical resources, and even through the simulation of virtual network adapter (of course, there must be at least one physical network adapter) to share the network.
Private cloud, public cloud, and hybrid cloud
A private cloud is a dedicated resource pool for each enterprise. It has many advantages, such as self-service resource deployment, elastic scalability, secure multiple users, effective resource utilization, and especially high security.
The public cloud uses the resources of the cloud computing service provider. It does not need to build servers or maintain them independently, but it needs to pay a specific fee and all the data is stored at the service provider. This is actually a very insecure behavior.
The hybrid cloud combines the private cloud and the public cloud. The core data is stored in the private cloud, while some unimportant data is stored in the public cloud.
In fact, these three types of cloud, are just some conceptual division, in essence, is a pile of piles of physical host resources.