虚拟化简单理解(简述虚拟化原理)

1. What is virtualization?
To put it simply, virtualization is the process of creating virtual (rather than physical) versions of some components. Virtualization can be applied to computers, operating systems, storage devices, applications or networks. However, server virtualization is the core of virtualization. Today's x86 servers are designed to run only one operating system and application at a time, creating challenges for IT departments. Therefore, even a small data center must deploy a large number of servers, and the capacity utilization rate of each server is only 5% to 15%, which is very inefficient by any standard.
Virtualization uses software to emulate hardware and create virtual computer systems. This allows enterprises to run multiple virtual systems—that is, multiple operating systems and applications—on a single server, which can lead to economies of scale and improved efficiencies.
2. Why virtualization?
Virtualization technology can solve many technologies that we could not solve before:
1. Server integration technology: This technology was difficult to complete without virtualization technology. Because everything is physical, it's difficult to integrate two servers that do relatively little work. However, with the advent of virtualization technology, this server consolidation technology becomes very easy. This technology requires the help of the 2 or 3 technologies I introduce below.
2. Load balancing technology:
Load balancing technology only installs a load balancer on each server, and then sets many scheduling algorithms and thresholds. To judge whether the pressure on the server at this moment is light or heavy. Then the server merging is completed according to the severity, and the merging is based on the third technology.
3. Dynamic migration technology: This technology is the foundation of the first two technologies, but it is not limited to the first two technologies. Its purpose is to migrate the virtual machines on the server to other servers while the server is on. The general working principle is to first simulate the hardware status of the server on the target server, then migrate the data, and finally release the information of the server.
4. Cloning technology: This technology sounds very similar to the above technology, but it is different. Cloning technology is to configure the environment of a server so that other machines can achieve the same effect as this machine through cloning technology. If you want to configure 100 or even 1,000 servers, this cloning technology is very impressive. The difference between it and dynamic migration is that when the server does not stop, dynamic migration requires that the migrated objects must share memory with each other, but cloning does not have this restriction.
5. Disaster recovery technology: Disaster recovery is an issue that all large companies must consider, because when some accidents occur, such as sudden power outages, hardware damage, floods, earthquakes, and a series of other situations, how to deal with the disaster? The data loss caused is minimized or even eliminated. This depends on the sixth technology.
6. Virtual snapshot technology: Virtual snapshot technology saves the current state of the virtual machine like a photo. Of course, I said it is easy. The implementation principle needs to be very complicated, including the CPU running status and the data in the memory. etc. In this way, these virtualization technologies are saved and can be quickly restored when a disaster occurs or some mistakes cause problems with the virtual machine.
7. Improve system availability. The availability here can only be a zero-down machine. In this case, we can maximize efficiency. The premise of a zero-down machine is that each server must have a mirror. There is a heartbeat line between the primary virtual machine and the secondary virtual machine to maintain the relationship between the two. When the heartbeat line stops, the secondary virtual machine starts immediately. , instead of the main virtual machine.
8. Security: We have a layer of VMM on the hardware layer until virtualization to detect the movements of each virtual machine at all times, including catching exceptions, solving door events, completing scheduling, etc. So when some risk factors come, due to the existence of VMM, we can detect the problem very quickly and solve it. This can be much faster than the previous hardware layer with the operating system directly on top.

Virtualization refers to virtualizing one computer into multiple logical computers through virtualization technology. It is a broad term that aims to simplify IT infrastructure. Virtualization objects can include virtualization of servers, Internet, desktops, and archive spaces. Since the concept of virtualization was proposed, its advantages have been known to most people, and server virtualization has become popular. For a long time in the past, half of the world's servers have been virtualized. Some of its own problems have gradually been exposed to everyone. For example, the process of server virtualization has subverted some of the original basic structures, making it impossible to guarantee the security of the virtualized server. On this basis, accessing some The software may cause harm to the leakage of personal privacy, which will also affect the shared virtual server, and its storage method also greatly increases the chance of information theft. It can be seen that the disadvantages brought by virtualization need to be solved urgently. According to a systematic study, most virtual servers are more vulnerable to attacks than physical servers.

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