What is hard disk virtualization, and the relationship between operating system and hard disk virtualization

Today's triple Small series for you to introduce what is hard disk virtualization and operating system and hard disk virtualization relationship.

Operating system virtualization is at the top of the operating system. This approach can greatly improve the server consolidation rate and resource utilization of many computing environments. When users use virtualized products and solutions, operating system virtualization is related to layers. Layer refers to the level of virtualization application. Application-based hardware virtualization solutions include layers that are processed on existing operating systems and layers that run directly on top of the hardware. This is the familiar "bare metal".

Early single-task mode

Early computers didn't actually have an operating system, because the operating system itself is to rely on computer hardware to execute a program, the operating system is a can provide other programs to facilitate the writing and running of programs, by the program to run the program, rather than their own to run, which is actually the operating system to provide the earliest virtualization performance.

For an earlier computer, you can run only one task. The entire computer can only be exclusive by this program, such as on the boot, from the floppy disk or other media to execute the program, until the execution or artificial terminal, after the execution of the ring to insert another media, reload the execution of another program, and in the execution process, Once an accident occurs, you can only rerun it.

Multi-task mode of operating system

The appearance of the operating system solves a lot of problems, the operating system itself is a program, computer appliances, first run the operating system, can load other programs at any time, that is, it can read from the floppy disk other program code, and switch to this band immediately let CPU execution, Switch back to the operating system immediately after execution. Stupid, but always wait for the program to finish before loading the next program execution. When the loaded program executes, can not do anything else, the operation of the operating system itself, the program module, any time of interruption, will interrupt the running program.

After the execution of the program, the CPU will be returned to the operating system, thereby continuing the operation of the operating system itself, which becomes a single task operating system, the typical representative is DOS.

Now the operating system for the system clock interruption, developed a special interrupt server program, that is, multitasking operating system scheduler, when the clock interrupt arrives, the CPU according to the interrupt vector table content, point to the scheduler's address portal, execute the Scheduler code, What the scheduler does is jump the CPU's execution to the memory address portal where each application resides, after each interruption, the scheduler, with a certain priority, points to the entry of a program that is not passed, so that it can switch to a very fine-grained application entry and cut out if a program has not been executed. The operating system will automatically save the running state of the program until the next turn, and then pull out to continue running.

With such virtualization, all programs running on top of the operating system will assume that they are running the hardware of a generation of computers.

The benefits of virtualization

The computer hardware and operating system described above, in fact, the computer system from the birth of the continuous process of this virtualization, today, the process of computer virtualization is still rapid development.

The benefits of virtualization are obvious, and virtualization transforms the complex logic of the lower layers into simple logic at the top, making it easy for humans to read, that is, "technology, people-oriented." Any technology is to make the upper logic more simple, not more complex, of course, the simpler the upper layer, the lower layer will do more work, the more complex.