Describe the characteristics of virtualized environments./Explain features to look for in a Virtualization Platform.

Characteristics of virtualized environments 

• Virtualization is a broad concept that refers to the creation of a virtual version of something, whether hardware, software environment, storage, or network. In a virtualized environment there are three major components: guest, host, and virtualization layer. The guest represents the system component that interacts with the virtualization layer rather than with the host, as would normally happen. The host represents the original environment where the guest is supposed to be managed. The virtualization layer is responsible for recreating the same or a different environment where the guest will operate. (see fig below)

• These environments support different applications and then implementation of Virtualization Technology. The most intuitive and popular is Hardware Virtualization, which also constitutes the original realization of the Virtualization Concept.

• Here in Hardware Virtualization Guest is represented by a system image which is comprised of an operating system and installed applications. These are installed on top of virtual hardware that is controlled and managed by the virtualization layer, also called the virtual machine manager. The host is instead represented by the physical hardware and in some cases the operating system, which defines the environment where the virtual machine manager is running.

Three major Components falls under this category in a virtualized environment:

1. GUEST:

The guest represents the system component that interacts with the virtualization layer rather than with the host, as would normally happen. Guests usually consist of one or more virtual disk files, and a VM definition file. Virtual Machines are centrally managed by a host application that sees and manages each virtual machine as a different application.

2. HOST:

The host represents the original environment where the guest is supposed to be managed. Each guest runs on the host using shared resources donated to it by the host. The operating system, works as the host and manages the physical resource management, and the device support.

3. VIRTUALIZATION LAYER:

The virtualization layer is responsible for recreating the same or a different environment where the guest will operate. It is an additional abstraction layer between a network and storage hardware, computing, and the application running on it. Usually it helps to run a single operating system per machine which can be very inflexible compared to the usage of virtualization.

OR,

The characteristics of virtualized environments

• In a virtualized environment there are three major components: guest, host, and virtualization layer.

• The guest represents the system component that interacts with the virtualization layer rather than with the host, as would normally happen.

• The host represents the original environment where the guest is supposed to be managed.

• The virtualization layer is responsible for recreating the same or a different environment where the guest will operate in the case of hardware virtualization, the guest is represented by a system image Compromising an operating system & installed application

• These are installed on top of Virtual hardware that is controlled & managed by the Virtualization layer also called the Virtual machine manager

The characteristics of virtualized environments

1. Partitioning: 

In virtualization, many applications and operating systems (OSes) are supported in a single physical system by partitioning (separating) the available resources.

2. Isolation:

 Each virtual machine is isolated from its host physical system and other virtualized machines. Because of this isolation, if one virtual instance crashes, it doesn’t affect the other virtual machines. In addition, data isn’t shared between one virtual container and another. 

3. Encapsulation: 

A virtual machine can be represented (and even stored) as a single file, so you can identify it easily based on the service it provides. In essence, the encapsulated process could be a business service. This encapsulated virtual machine can be presented to an application as a complete entity. Therefore, encapsulation can protect each application so that it doesn’t interfere with another application.

4. Increased Security

The ability to control the execution of a guest in a completely transparent manner opens new possibilities for delivering a secure, controlled execution environment. The virtual machine represents an emulated environment in which the guest is executed. All the operations of the guest are generally performed against the virtual machine, which then translates and applies them to the host.

5. Managed Execution

 Virtualization of the execution environment not only allow increased security but a wider range of features can be implemented. In particular, sharing, aggregation, emulation, and isolation are the most relevant.

OR, The characteristics of virtualized environments/ features to look for in a Virtualization Platform

 1. Reduction of Capital Expenditures (CAPEX): 

Server usage levels are typically modest, averaging approximately 15%. Virtualization has the potential to double throughput. This implies that a corporation may utilize less hardware and save money on electricity. It is important to note that this must be balanced against the total cost of ownership of the virtualization platform.

2. System Consolidation: 

An organization decreases the number of physical servers necessary by running numerous applications and operating systems. This is a method of utilizing computer server resources efficiently to decrease the total number of servers or server locations required by a company.

3. Ease of System Management:

 Easy administration in this sense refers to how quickly new services such as platform as a service (PaaS), infrastructure as a service (IaaS), and software as a service (SaaS) can be implemented. It also refers to the agility and rapidity with which new application stacks are deployed.

4.  Platform Maturity: 

Virtualization is a costly long-term investment that will be squandered if suppliers are swapped. As a result, new market entrants may not be a good option for mission-critical data centers.

5. Hardware Compatibility: 

Hardware challenges with virtualizing platforms include outright incompatibility and sub-optimal performance. Hosted hypervisors often support the widest range of hardware types, whereas bare-bonesvirtualizers are often picky about supported hardware. If you intend to reuse existing gear, be sure that your platform of choice supports it.

6. Total Cost of Ownership: 

The total cost of ownership includes more than simply the cost of acquiring a virtualization platform. Additional costs should be considered, such as guest licensing, training and support, and hardware. The acquisition of sophisticated management is one expense component that is frequently overlooked. These are typically not included in the initial purchase price.