Virtualization Architecture In Cloud Computing

Virtualization Architecture In Cloud Computing

Consider a vast, mighty physical server in a data center. It is an engineering wonder, though it is idle 90 percent of the time, performing one operation and wasting power. But now, consider what would happen with the same server were you to make a magic that broke it into a dozen independent and secure and fully-functional servers, each with its own operating systems and applications? It is not magic; it is the main idea of virtualization.

The big game changer is the virtualization technology that enables the existence of modern cloud computing. It is the process of developing a software-based, or virtual, copy of a physical computing resource. This may be a server, a storage device, a network or even an operating system. Virtualization enables previously unimaginable efficiency, agility, and scalability by decoupling the software and underlying physical infrastructure.

This deep dive will examine the complexity of cloud computing, specifically focusing on its virtualization architecture. We are going to deassemble it, find the key elements of it, and discuss the comparison of the most prominent types of virtualization architectures and how it perform alongside some current solutions such as containerization, to drive the digital world. As an IT expert, a developer or even a technology enthusiast, it is essential to comprehend this base technology in order to grasp the cloud.

What is Virtualization? The Core Concept Explained

Simply put, the heart of what virtualization is can be answered in one term: it is abstraction. It places a slim, smart layer of software between the actual hardware and the operating systems that desire to employ it. The hypervisor, this layer, deceives each operating system that it has full and exclusive access to the underlying CPU, memory, storage and network controllers.

Imagine the physical infrastructure such as a server, is a block of apartments. Building walls, installing separate plumbing, electricity meters and developing individual and self-contained apartments in that building is the process that is referred to as virtualization. Atoms are secluded units, each corresponding to an apartment (Virtual machine or VM). One apartment (e.g. crashed OS) isn’t going to impact the neighbors, and each tenant (application) is free to adorn and utilize their space as they see fit, irrespective of what other tenants are up to.

This abstraction brings enormous value that are the USPs of the cloud

Also Read : What is Virtualization?  

Server Consolidation

Before the adoption of virtualization, it was common to have one application on each physical server. This was to prevent incompatibility between applications and their respective supporting software stacks; however, it resulted in a phenomenon called “server sprawl,” in which data centers had idle hardware. These servers typically ran only at 5-15 percent of their capacity, which proved a considerable waste of capital outlay, power usage, thermal cooling, and physical space. 

This model of operation was inherently neither economic nor ecological because it demanded an increasing infrastructure to accommodate new applications. Virtualization goes directly to the root of this inefficiency, allowing server consolidation. One large, physically secure server can be subdivided into several secure and isolated virtual machines (VMs), each with the capability to deploy its own operating system and applications. 

Isolation and Security

One of the fundamental principles of a healthy IT infrastructure is the isolation of various applications and services to maintain stability and security. In a classic shared-server configuration, an erroneously configured application, a rogue process, or a security flaw in a single service can burn out all available resources or present an avenue to an attacker to bring down the entire system and all other services on that machine. This riskiness tended to push organizations into the expensive one-application-per-server model as this was the only sure method of achieving isolation.

A much more elegant and hardware-efficient solution is achieved by means of isolation and security with virtualization. The hypervisor isolates the virtual machines such that each one exists as an independent entity, which is entirely independent of the host system and any other virtual machines. An error, like a crash of the operating system (the blue screen of death) in one VM is completely isolated in that virtual environment and does not interfere with the stability of adjacent VMs or the host. 

Agility and Provisioning

Physical hardware Provisioning of a new server was a manual and time-consuming process in the era of physical hardware. It included long procurement times for new equipment, manual installation of hardware in data center racks, complicated cabling, and extensive configuration of an operating system and all the necessary drivers and applications. This procedure may take days, possibly weeks, to accomplish, creating a major bottleneck to development teams and business units that require infrastructure to roll out new applications or services. This was not fast enough to encourage innovation and IT was not able to react swiftly to the business demands.

Virtualization adds unprecedented agility and provisioning through the treatment of server instances as software files. With a central management panel, an administrator is allowed to roll out a new fully configured server- a virtual machine- in just a few minutes on a pre-built template. 

Disaster Recovery and Portability

Physical server-based traditional disaster recovery (DR) plans were complicated and expensive, frequently necessitating the same set of redundancy hardware at a backup facility. Their physical form made them physically inflexible; it was almost impossible to move a live workload between physical machines without causing substantial downtime and even the backups themselves were bulky and not easily put back into dissimilar hardware. This rendered the strong DR solutions a cost that was prohibitive to many organizations exposing them to prolonged downtime.

Virtualization has a fundamental impact on the disaster recovery and portability landscape because a virtual machine is packaged in a few files (primarily a configuration file and virtual disk files). It is groundbreaking in its portability. These files are fast and straightforward to back up, copy and transfer anywhere. With the capability of vMotion or Live Migration, live VMs can be migrated between physical hosts with zero downtime and thus proactive maintenance and load balancing become possible. 

The Pillars of Virtualization Architecture: Hypervisors, VMs and Networks.

To see how this magic works, we must look at the basic building blocks that make up any virtualization architecture.

The Hypervisor: The Conductor of the Orchestration

The absolute keystone of virtualization is the hypervisor, or Virtual Machine Monitor (VMM). The software layer that is in place is either on the hardware itself or on a host operating system and is the one that creates, executes and oversees all the virtual machines.The hypervisor has several critical duties:

  • Resource Allocation: It assigns physical resources (CPU time, memory, disk I/O, network bandwidth) to each VM.
  • Scheduling: It ensures the timing of instructions from several VMs to the physical CPU cores is handled fairly and efficiently.
  • Isolation: It enforces rigid barriers among VMs, so that they do not interfere with one another.
  • Hardware Abstraction: It exposes a standardized guest VM to each virtual hardware, concealing the details of the underlying physical hardware. It is what contributes portability of VMs.

Typical virtualization packages containing hypervisors are VMware vSphere/ESXi, Microsoft Hyper-V, Citrix Hypervisor, and the free KVM (Kernel-based Virtual Machine).

The Virtual Machine (VM): The Stand-alone Server

A Virtual machine (VM) is a computer-like software emulation of a physical computer. It is a totally distinct environment with its own operating system (so-called guest OS) and programs as though it were a physical machine.

Every VM contains a set of important files:

  • Configuration File: Sets the hardware configuration of the VM (number of virtual CPUs, for example, amount of RAM, network connections, and so on).
  • Virtual Disk File: It works like the hard disk of the VM, on which the guest operating system, applications and data are stored.
  • Memory File: Is saved when a VM is suspended, and preserve its precise state.

The beauty of VM is that it is complete and independent. It is possible to run a Windows Server guest operating system on a VM in a physical server running Linux and the other way round. This is the reason why VMs are the primary building block of the initial generation of services building cloud virtual infrastructure such as AWS EC2, Azure Virtual Machines, and Google Compute Engine.

Read More : What is Virtual a Machine?

The Virtual Network

A virtual network is a logical representation of actual physical network, which the hypervisor reinvents in software. It enables VMs to interact among themselves, with the world and with their host computer.

Hypervisor assigns vSwitches ,vRouters, and vNICs to every VM. This allows complex network topologies to be built entirely in software and it is essential to multi-tier applications (e.g. a web server VM, an application server VM, and a database server VM connected by a secure virtual network). This is one of the basic components of software-defined networking (SDN) on the cloud.

Two Major Architectures Of Virtualization

The architecture of virtualization in cloud computing is mainly concerned with the placement and the type of hypervisor it employs. Virtualization architectures are of two basic kinds, Bare Metal and Hosted.

Type 1 Hypervisor (Bare Metal Architecture)

This is the most widespread and efficient architecture employed in the enterprise data centers and with the public clouds.

In Bare Metal Architecture, the installer of the hypervisor is directly placed on the hardware of physical server. It does not need or depend on an underlying host operating system. It is very efficient, secure and performant because it communicates directly with the hardware. It is usually referred to as a native or embedded hypervisor.

How it Works: The physical server will start directly into the hypervisor. The hypervisor then carves out physical resources of the server and allocates them to the VMs.

Advantages

  • Performance: There is no host OS overhead, and therefore, more resources are allocated to VMs and their performance is close to native.
  • Security: There is a smaller attack surface in the absence of a general-purpose host OS.
  • Stability: The fewer the number of layers, the less the chances of instability.
  • Examples: VMware ESXi, Microsoft Hyper-V, Citrix Hypervisor, and KVM (when it is installed on a bare bones OS optimized to support virtualization)
  • This is the architecture that is the workhorse of cloud providers and it is the basis of their scalable and reliable virtual infrastructure services.

Hosted Architecture (The Type 2 Hypervisor)

This architecture is used more often in desktop applications, development and testing.

Hosted architecture In a Hosted architecture, the hypervisor is executed as a software app within the standard host operating system (such as Windows, macOS, or Linux). The VMs are then executed as processes in such a host OS.

Operation: The physical server is a regular OS. The user installs a virtualization software application (e.g. Oracle VM VirtualBox, VMware Workstation, Parallels Desktop). This application then generates and manages the VMs.

Advantages

  • Simility: Absolutely simple to set up and configure; it does not have to be reconfigured to the whole server.
  • Hardware Compatibility: Taps into the wide-ranging hardware drivers of the host OS.

Disadvantages

  • Performance Overhead: The host operating system itself is a resource consumer, causing reduced performance to VMs.
  • Less Secure: Host OS is a bigger attack area. A breach of the host OS breaches all VMs.
  • Use Case: Ideal when a developer wants to test an application on a Linux VM on his/her Windows computer.

The Modern Evolution: Virtualization and Containerization

Although the power of traditional virtualization using VMs is enormous, it has a disadvantage a complete copy of an operating system is needed in each VM, thus consuming huge amounts of CPU, RAM, and storage resources. It gave way to the emergence of a lighter-weight substitute: containerization.

It is essential to know the connection, and distinction between Virtualization and Containerization.

  • Virtualization (with VMs): Decouples the physical hardware. Every VM has a guest OS, binaries, libraries and the application over it. It is very isolating.
  • Containerization (with Containers): Abstraction of the operating system kernel. A Container is a standardized piece of software that wraps up code and all its dependencies (libraries, frameworks) such that the application will run fast and reliably across one computing environment to another. Several containers are operating on the same OS kernel.

Container technologies such as Docker and orchestration platforms such as Kubernetes (K8s) have become massively popular in the construction of modern, cloud-native applications. Their density and speed are incomparable, as running hundreds of containers on one server is possible, whereas running dozens of VMs is not.

This is not a story of replacement. It’s one of synergy. The most widespread trend in the current cloud computing would be to deploy a container orchestration framework, such as Kubernetes over a set of virtual machines. This is a combination of high security and isolation of VMs (as with the Bare Metal Architecture hypervisor) and container agility and density. The VMs offer a multi-tenant, stable, and secure foundation, whereas the containers provide fast deployment and scaling of applications.

Virtualization Architecture in Cloud Computing: A Practical View

But what happens to all this on a public cloud such as AWS, Azure or GCP?

  • The Foundation: There is the presence of huge data centers with physical servers operated by the cloud provider.
  • The Hypervisor Layer: In them they install a fast, hardened Type 1 hypervisor, such as KVM, Xen or a commercial version, on those servers. This is the invisible engine.
  • The Resource Pool: The hypervisor pools the resources available in all of these physical servers and makes them a large, shared reservoir of compute, storage, and networking power.
  • The Service Offering: When you, as a customer, order a Virtual Machine (e.g., an AWS EC2 instance), the cloud management software tells a hypervisor to create a new VM, based on a template, with the CPU, memory, and storage that you specify.
  • The Virtual Network: At the same time, it attaches your new VM to a virtual network (e.g. an AWS VPC) that you manage and uses firewalls, routing and IP addresses all in software.

The Result: A fully operational, secure and connected server is available within a matter of seconds. You have no idea what physical infrastructure you are on at any point in time–you are totally abstracted. That is the final manifestation of virtual infrastructure services.

This architecture enables the cloud providers to realize massive multi-tenancy, in which thousands of customers workloads are able to run safely and autonomously on shared physical hardware, and they are able to scale the resources up or down as needed.

Conclusion

Since its simple inception as a server consolidation technology, virtualization has become the basic architecture of cloud computing. The very idea of its virtualization, which is the separation of resources in place of the physical constraint with which they are bound, has made possible a radical transformation in the way we construct, deploy and run IT.

The decision to use Bare Metal Architecture for maximum performance, Hosted architecture for simplicity, or full Virtual Machine isolation to achieve the unattainable agility of lightweight Containers is not about finding a winner. It is a matter of the choice of the appropriate tool to the proper job. Awareness of the nature of virtualization architectures and its elements- the hypervisor, the virtual network and the underlying software that supports the process of virtualization is what every individual needs to do well in the contemporary technological environment.

However, with the ongoing development of cloud computing, the principles of virtualization will remain at its core, and they will keep propelling innovation, effectiveness, and the unstoppable rate of digital transformation. Our globalized world runs on it.

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About the Author
Posted by Dharmesh Gohel

I turn complex tech like CPUs, GPUs, cloud systems and web hosting into clear, engaging content that’s easy to understand. With a strategic blend of creativity and technical insight, I help readers stay ahead in a fast-moving digital world.

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