Cloud Computing -Server Virtualization
Virtualization is the core technology for cloud computing.
It is a process of taking a physical entity of a large capacity and dividing it into multiple smaller independent logical entities.
Hence, cloud providers can virtualize their physical resources and share them between multiple customers and organizations.
Virtualization in cloud computing can be the creation of a virtual version of a server, a desktop, a storage device, an operating system, or network resources.
Server Virtualization
Server Virtualization creates logically separate servers called virtual machines from physical servers. A physical server has its pool of resources in terms of CPU, memory, and disk space.
When server virtualization happens, these resources are divided and allocated to the virtual machines created within the physical server. Hence, a virtual machine behaves like an independent logical server with its CPU, memory, and disk.
A Hypervisor manages this server virtualization process.
Hypervisor
A Hypervisor is a piece of software that runs on a physical server. There are mainly two types of hypervisors –
Type 1 Hypervisor:
Type 1 hypervisor helps with server virtualization. It is installed directly on the server hardware and interacts with the server’s CPU, memory, and disk storage. Hence this hypervisor is also known as the Bare-Metal Hypervisor.
As shown in the figure below, the physical server is at the bottom, the hypervisor is in the middle, and the logical virtual machines run at the top.
Each virtual machine is a separate logical entity and will have its copy of the operating system (also known as the Guest Operating System), applications, and dependencies. Each virtual machine can have a different operating system.
This hypervisor offers high availability and resource management. It has direct access to the system hardware and enables better scalability, stability, and performance. Some examples of Type 1 hypervisors are VMWare ESXi, Windows HyperV, and Citrix XenServer.
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Type 2 Hypervisor:
Type 2 Hypervisor is for end-user or desktop virtualization experience. It runs as an application on an operating system instead of directly on a physical server. As shown below, a layer of the host operating system sits between the physical server and the hypervisor.
This hypervisor can be used by end-users on their desktops when they want isolated environments on their host operating systems. They can have the physical server, the host operating system, the type 2 hypervisor, and the independent virtual machines with their guest operating systems and application.
It helps ease system configuration along with simplifying management tasks. However, the host operating system can potentially limit performance and expose security flaws. Some examples would be Oracle VirtualBox and VMWare Player.
Uses of a Hypervisor –
1. To divide a physical server into multiple virtual machines and allocate the resources between them.
2. To keep the virtual machines logically separate so that any issue in one of these does not affect the others.
3. Help identify the number of virtual machines that can run on a single physical server.
Server Virtualization Benefits:
1. Physical servers have high processing power, memory, and disk capacities today. One server for one application would mean many servers, capacity wastage, and data centers with a lot of power, cooling, and space requirements. With Virtualization, multiple virtual machines run on a single physical server, thus leading to maximum use of the server and savings in power consumption, cooling, space requirements, and maintenance.
2. It is easy to spin up a new virtual machine than to set up a new physical server altogether. Hence Virtualization gives better agility and speed to businesses today to set up new infrastructure for their needs.
3. Virtualization can help reduce downtime of applications due to hardware failures as the virtual machines are portable and can be moved from one hypervisor to another, thus making the applications available at all times.
Hope this article helped you with some insight into server virtualization.
In my next article, we will try to understand this technology in some of the public clouds- Elastic Compute Cloud (EC2) in AWS, Virtual Machine in Azure, and Compute Engine in Google Cloud.
Regards,
Ramya
