If we talk about levels of virtualization implementation in cloud computing, then the first thing that comes into mind is why there are levels in virtualization.
Therefore, to get this, let us look at the traditional and virtualized computer systems. If one knows the main difference between these two models, one can easily understand the levels defined for virtualization in cloud computing.
Hence, traditional systems will have the hardware set initially, and then that particular system will have its operating system. Then it will have various services which users were excessing globally.
Hence, the operating system act as an interface between the hardware and the application.
With Virtualized system, then above the host machine, a virtualized layer was installed that gives services to the users (guest operating system) in the virtual pattern.
Therefore, all the hardware resources in the virtualized computing system that user requests are converted in virtual form using the virtualization layer, and these conversions need some implementations.
Levels of Virtualization Implementation in Cloud Computing
In simple terms, virtualization is a computer architecture technology by which many virtual machines (VMs) can run in the corresponding hardware machine.
The primary idea of VMs is dated back to the 1960s. Therefore, it aims to improve resource sharing by several users and enhance computer performance in resource utilization and application adaptability.
Now, virtualization is a regular practice in enterprise IT architecture. It is also the technology that encourages cloud computing economics. Hence, virtualization enables cloud providers to help users with their existing physical computer hardware.
Also, it allows cloud users to acquire only the computing resources they need when they need it and scale those resources cost-effectively as their workloads expand.
There are three ways to build virtual servers: full virtualization, para-virtualization, and OS-level virtualization.
They all experience a few common traits. The physical server is named the host, and the virtual servers are called guests.
Therefore, virtual servers act like physical machines. The specific system uses a distinctive approach to allocate physical server resources to virtual server requirements.
- Full virtualization uses a specific software called a hypervisor. The hypervisor interacts straight with the physical server’s CPU and disk space and serves as a virtual server’s operating systems program.
- Hence, the hypervisor keeps each virtual server wholly independent and unaware of the separate virtual servers working on the physical machine.
- The hypervisor observes the physical server’s resources. As virtual servers run applications, the hypervisor sends resources from the physical machine to the relevant virtual server.
- The para-virtualization program is a little different. Unlike the full virtualization technique, the guest servers in a para-virtualization system are aware of one another.
- Therefore, a para-virtualization hypervisor doesn’t require as much processing power to control the guest operating systems.
- Each OS is already conscious of the demands the other operating systems are setting on the physical server. The entire system works collectively as a cohesive unit.
- An OS-level virtualization program doesn’t use a hypervisor at all. Instead, the virtualization ability is part of the host OS, which fulfills all the functions of a fully virtualized hypervisor.
- The most unusual limitation of this approach is that all the guest servers must work on the same OS. Hence, each virtual server remains free from all the others, but you can’t mix-match operating systems between them.
- As all the guest operating systems must be the same, this is called a homogeneous environment.
Let us now explain different levels of virtualization in cloud computing.
It is not easy to set up virtualization. Your computer works on an operating system that gets configured on some specific hardware.
Thus, it is not feasible or straightforward to run a different operating system using the corresponding hardware.
To do this, one will need a hypervisor. Hence, the role of the hypervisor is to bridge between the hardware and the virtual operating system, which enables smooth functioning.
Meanwhile, talking of the Implementation levels of virtualization in cloud computing, five levels are commonly used. Let us now look firmly at each of these levels of virtualization implementation in cloud computing.
At the ISA level, virtualization can work via emulating a given ISA by the ISA of the host machine. For instance, MIPS binary code can operate on an x86-based host machine with the help of ISA emulation.
Thus, this strategy makes it possible to run a large volume of legacy binary code written for several processors on any provided different hardware host machine.
The first emulation method is through code interpretation. Therefore, an interpreter program defines the source instructions to target instructions one by one.
Activity happenings within the Instruction Set Architecture Level (ISA):
- The hardware on the physical server in cloud computing has its own instruction set that it will process.
- Hence, these instructions act as an interface between hardware and software. Therefore, by the instruction set, hardware immediately assigns its services to its upper layers.
- The emulator serves as an interpreter, and the fundamental role of this is to set communication between the virtualization and hardware layers in cloud computing.
Mapping of the instruction
- Instructions that the emulator gets for the resources from the virtual machine can get mapped to the hardware instruction presented in the host machine.
- Therefore, after the processing emulator got the result back from the host machine, it sent services to the user with the help of the virtual machine.
Hardware-Abstraction level virtualization is available right on top of the bare hardware. On the one side, this approach produces a virtual hardware environment for a VM.
On the other side, the process controls the underlying hardware through virtualization.
Therefore, the purpose is to virtualize computer resources, such as processors, memory, and I/O devices. Also, the aim is to upgrade the hardware utilization rate by various users concurrently.
Activity happenings within the Hardware-Abstraction level (HAL):
Hardware resources in the host machine get mapped using a virtualization layer to the virtual resources present on the guest operating system. Thus, the virtual machine will create for all of them.
Hence, virtualized computing system holds thousands of resources. All of them need some directions for processing, which was not an easy task. And due to, this instruction was classified into two primary forms to make the processing smooth.
- Non-privileged instruction– These instructions execute directly without interfering with other tasks.
- Privileged instruction– These instructions require some modification before it executes.
The virtualization model can create an abstract layer between the operating system and the user application at this operating system level.
It is an isolated container on the operating system and the physical server, which uses the software and hardware. Thus, each of these then operates in the form of a server.
Therefore, when there are numerous users and no one wants to share the hardware, then at this point, the virtualization level comes into use.
Each user will get one virtual environment using a virtual hardware resource that is dedicated. Hence, in this manner, there is no issue of any conflict.
Activity happenings within the Operating System Level:
- Any hardware which is in a virtualized environment will process within this operating system.
- And the essential requirement at the operating system level is that all the user systems on the virtualized environment will hold the same family operating system. Otherwise, we can’t transfer the service to the users.
Most utmost applications use APIs exported by user-level libraries rather than practicing lengthy system calls by the OS.
Since most of the systems provide well-documented APIs, such an interface becomes another applicant for virtualization.
Therefore, virtualization with library interfaces is possible by checking the communication link between applications and the system through API hooks.
Activity happenings within the Library Support Level:
- Use of the application programming interface (API).
- At this level, the emulator’s idea worked as a tool and provided the guest operating system to practice the resources they want. In short, users use the emulator to run different applications of the other operating systems.
The application-level virtualization works where there is a desire to virtualize only one application and is the last of the implementation levels of virtualization in cloud computing.
One does not require to virtualize the complete environment of the platform.
Therefore, it generally works when you run virtual machines that practice high-level languages. Also, it lets the high-level language programs compiled be of use in the application level of the virtual machine that runs seamlessly.
Activity happenings within the Library User-Application Level:
- Virtual machine as an application operates at the user system with the help of the virtualization layer.
- Also, the users excess the services if the environment in which user and host were of a different type.
Overall, hardware and OS support will produce the highest performance. Nevertheless, the hardware and user-application levels are also the costliest to implement. Therefore, user isolation is the most challenging to achieve. ISA implementation extends the best application flexibility.
There are, in total, five implementation levels of virtualization in cloud computing. However, every company may not use each one of the varying levels of virtualization implementation in cloud computing.
Therefore, the level used is totally on the company’s work and its preference for the levels of virtualization. The company will use the virtual machine to develop and test across multiple platforms.
Cloud-based applications are on the rise, which makes virtualization a must-have thing for enterprises worldwide.