What is hardware virtualization?

Hardware virtualization is the method used to create virtual versions of physical desktops and operating systems. It uses a virtual machine manager (VMM) called a hypervisor to provide abstracted hardware to multiple guest operating systems, which can then share the physical hardware resources more efficiently. Hardware virtualization offers many benefits, such as better performance and lower costs.

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How does hardware virtualization differ from virtualization?

By separating resources or requests for service from the physical delivery of that service, virtualization technology enables administrators to distribute resources across the enterprise and use infrastructure more efficiently. Virtualization is the technology that enables cloud computing by allowing different computers to access a shared pool of resources. Virtualization technologies are used in a range of system layers to consolidate workloads and make IT environments more scalable and flexible.

Hardware virtualization is a type of virtualization that has made it possible for companies to efficiently employ underused physical hardware. Full utilization of the physical resources available in powerful servers, for example, reduces the total cost of ownership for server deployments.

What are the components of hardware virtualization?

Hardware virtualization is structured in layers consisting of the following components:

  • The hardware layer, or virtualization host, contains the physical server components such as CPU, memory, network, and disk drives. This is the physical hardware on which virtualization takes place. It requires an x86-based system with one or more CPUs to run all supported guest operating systems.
  • The hypervisor creates a virtualization layer that runs between the OS and the server hardware, allowing many instances of an operating system or different operating systems to run in parallel on a single machine. Hypervisors isolate operating systems and applications from the underlying computer hardware, or the host machine, from the virtual machines that use its resources.
  • Virtual machines are software emulations of a computing hardware environment and provide the functionalities of a physical computer. Virtual machines themselves consist of virtual hardware, a guest operating system, and guest software or applications.

How does hardware virtualization work?

Hardware virtualization enables a single physical machine to function as multiple machines by creating simulated environments. The physical host uses software called a hypervisor that creates an abstraction layer between the software and hardware and manages the shared physical hardware resources between the guest and host operating systems. The hypervisor connects directly to the hardware and enables it to be split into multiple distinct environments or virtual machines. These VMs use the resources of the physical host, including CPU, memory, and storage, which are allocated to the guests as needed. When done for server platforms, hardware virtualization is called server virtualization. Hardware virtualization makes it possible to use a physical machine’s full capacity and, by isolating VMs from one another, to protect against malware.

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What are the different types of hardware virtualization?

Full virtualization

In full virtualization, the hardware architecture is completely simulated, enabling an unmodified guest operating system to be run in isolation. Data is abstracted from the underlying hardware by the virtualization layer, isolating service requests from the physical hardware that facilitates them. In this scenario, the guest operating system is unaware that it is in a virtualized environment, and therefore hardware is virtualized by the host operating system so that the guest can issue commands to what it thinks is actual hardware. However, these are just simulated hardware devices created by the host, and the hypervisor translates all OS calls. This type of virtualization isolates VMs from the host OS and one another, enabling total portability of VMs between hosts regardless of underlying hardware.  

Paravirtualization

In paravirtualization, the source code of an operating system is modified to run on top of a virtual machine monitor. This OS modification is required for the guest OS to communicate through calls to the API provided by the hypervisor (known as hypercalls). In this scenario, the guest OS is aware that it is a guest OS in a virtual machine environment and receives information on the other operating systems on the same physical hardware, enabling them to share resources rather than emulate an entire hardware environment. In paravirtualization, the guest OS communicates directly to the hypervisor, improving performance and efficiency.   

Operating system–level virtualization

Managed desktops take away a big chunk of work from the IT department, as this cloud-based infrastructure is maintained and updated by the DaaS provider. With a managed desktop solution, downtime is minimized and help desk calls are considerably lowered, as resource demand does not overstress end user devices.

System-level virtualization

With the simple deployment of managed desktops, IT can get temporary workers set up in relatively little time—saving hours of labor. And, IT will have full control to give your temporary employees access to only the resources they need to work.

Hardware-assisted virtualization

In hardware-assisted virtualization, the computer’s physical components provide the architectural support for the virtual machine manager, or hypervisor. The combination of hardware and software allows different guest operating systems to run in isolation simultaneously on a host computer, preventing potentially harmful instructions from being executed directly on the host machine. These physical components primarily consist of the host processors, which optimize virtualization in a number of ways.

Citrix solutions for hardware virtualization

Citrix Hypervisor boosts IT flexibility with an open-source virtualization platform that enables you to manage different workload types, mixed operating systems, and complex storage or networking requirements. With Citrix Hypervisor, you can:

  • Consolidate multiple VMs onto a physical server
  • Reduce the number of separate disk images to be managed
  • Schedule zero downtime maintenance by live migrating VMs
  • Assure availability of VMs by using high availability to configure policies that restart VMs on another server in case one fails
  • Increase portability of VM images

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