What is Virtualization?

Virtualization is a proven software technology that is rapidly transforming the IT landscape and fundamentally changing the way that people compute.

Today’s powerful x86 computer hardware was originally designed to run only a single operating system and a single application, but virtualization breaks that bond, making it possible to run multiple operating systems and multiple applications on the same computer at the same time, while increasing the utilization and flexibility of hardware.

Virtualization is a technology that can benefit anyone who uses a computer, from IT professionals and Mac enthusiasts to commercial businesses and government agencies. Join the millions of people around the world who use virtualization to save time, money and energy while achieving more with the computer hardware they already own.

How does it Work?

In essence, virtualization lets you transform hardware into software. Use software such as VMware ESX to transform or “virtualize” the hardware resources of an x86-based computer—including the CPU, RAM, hard disk and network controller—to create a fully functional virtual machine that can run its own operating system and applications just like a “real” computer.

Multiple virtual machines share hardware resources without interfering with each other so that you can safely run several operating systems and applications at the same time on a single computer.

The VMware approach to virtualization inserts a thin layer of software directly on the computer hardware or on a host operating system. This software layer creates virtual machines and contains a virtual machine monitor or “hypervisor” that allocates hardware resources dynamically and transparently so that multiple operating systems can run concurrently on a single physical computer without even knowing it.

However, virtualizing a single physical computer is just the beginning. VMware offers a robust virtualization platform that can scale across hundreds of interconnected physical computers and storage devices to form an entire virtual infrastructure.

Virtualization is a technology that can benefit anyone who uses a computer. Millions of people and thousands of organizations around the world—including all the Fortune 100—use VMware virtualization solutions to reduce IT costs while increasing the efficiency, utilization and flexibility of their existing computer hardware. Read below to discover how virtualization can benefit your organization.

Top 5 Reasons to Adopt Virtualization Software

  1. Server Consolidation and Infrastructure Optimization—Virtualization makes it possible to achieve significantly higher resource utilization by pooling common infrastructure resources and breaking the legacy “one application to one server” model.
  2. Physical Infrastructure Cost Reduction—With virtualization, you can reduce the number of servers and related IT hardware in the data center. This leads to reductions in real estate, power and cooling requirements, resulting in significantly lower IT costs.
  3. Improved Operational Flexibility & Responsiveness—Virtualization offers a new way of managing IT infrastructure and can help IT administrators spend less time on repetitive tasks such as provisioning, configuration, monitoring, and maintenance.
  4. Increased Application Availability and Improved Business Continuity—Eliminate planned downtime and recover quickly from unplanned outages with the ability to securely backup and migrate entire virtual environments with no interruption in service.
  5. Improved Desktop Manageability & Security—Deploy, manage and monitor secure desktop environments that end users can access locally or remotely, with or without a network connection, on almost any standard desktop, laptop or tablet PC.

A virtual machine is a tightly isolated software container that can run its own operating systems and applications as if it were a physical computer. A virtual machine behaves exactly like a physical computer and contains its own virtual (ie, software-based) CPU, RAM hard disk and network interface card (NIC).

An operating system can’t tell the difference between a virtual machine and a physical machine, nor can applications or other computers on a network. Even the virtual machine thinks it is a “real” computer. Nevertheless, a virtual machine is composed entirely of software and contains no hardware components whatsoever. As a result, virtual machines offer distinct advantages over physical hardware.

Virtual Machines Benefits

In general, VMware virtual machines possess four key characteristics that benefit the user:

  • Compatibility—Virtual machines are compatible with all standard x86 computers.
  • Isolation—Virtual machines are isolated from each other as if physically separated.
  • Encapsulation—Virtual machines encapsulate a complete computing environment.
  • Hardware independence—Virtual machines run independently of underlying hardware.


Just like a physical computer, a virtual machine hosts its own guest operating system and applications and has all the components found in a physical computer (motherboard, VGA card, network card controller, etc). As a result, virtual machines are completely compatible with all standard x86 operating systems, applications and device drivers, so you can use a virtual machine to run all the same software that you would run on a physical x86 computer.


While virtual machines can share the physical resources of a single computer, they remain completely isolated from each other as if they were separate physical machines. If, for example, there are four virtual machines on a single physical server and one of the virtual machines crashes, the other three virtual machines remain available. Isolation is an important reason why the availability and security of applications running in a virtual environment is far superior to applications running in a traditional, non-virtualized system.


A virtual machine is essentially a software container that bundles—or “encapsulates” —a complete set of virtual hardware resources, as well as an operating system and all its applications, inside a software package. Encapsulation makes virtual machines incredibly portable and easy to manage. For example, you can move and copy a virtual machine from one location to another just like any other software file or save a virtual machine on any standard data storage medium, from a pocket-sized USB flash memory card to an enterprise storage area networks (SANs).

Hardware Independence

Virtual machines are completely independent from their underlying physical hardware. For example, you can configure a virtual machine with virtual components (eg, CPU, network card, SCSI controller) that are completely different from the physical components that are present on the underlying hardware. Virtual machines on the same physical server can even run different kinds of operating systems (Windows, Linux, etc).

When coupled with the properties of encapsulation and compatibility, hardware independence gives you the freedom to move a virtual machine from one type of x86 computer to another without making any changes to the device drivers, operating system, or applications. Hardware independence also means that you can run a heterogeneous mixture of operating systems and applications on a single physical computer.

Virtual Machines: Building Blocks of the Virtual Infrastructure

Virtual machines are a fundamental building block of a much larger solution—the virtual infrastructure. While a virtual machine represents the hardware resources of an entire computer, a virtual infrastructure represents the interconnected hardware resources of an entire IT infrastructure including computers, network devices, and shared storage resources. Organizations of all sizes use VMware solutions to build virtual server and desktop infrastructures that improve the availability, security, and manageability of mission-critical applications.

The introduction of virtualization technology presents a number of opportunities for driving capital and operational efficiency above and beyond the simple benefit of safe partitioning. VMware’s customers have harnessed the power of virtualization to better manage IT capacity, to provide better service levels, and to streamline IT processes. We have coined a term for virtualizing the IT infrastructure–we call it the “virtual infrastructure”.

What is a Virtual Infrastructure?

In essence, a virtual infrastructure is a dynamic mapping of physical resources to a business’ needs. While a virtual machine represents the physical resources of a single computer, a virtual infrastructure represents the physical resources of the entire IT environment, aggregating x86 computers and their attached network and storage into a unified pool of IT resources.

Structurally, a virtual infrastructure consists of the following components:

  • Single-node hypervisors to enable full virtualization of each x86 computer.
  • A set of virtualization-based distributed system infrastructure services such as resource management to optimize available resources among virtual machines.
  • Automation solutions that provide special capabilities to optimize a particular IT process such as provisioning or disaster recovery.

By decoupling the entire software environment from its underlying hardware infrastructure, virtualization enables the aggregation of multiple servers, storage infrastructure and networks into shared pools of resources that can be delivered dynamically, securely and reliably to applications as needed. This pioneering approach enables organizations to build a computing infrastructure with high levels of utilization, availability, automation, and flexibility using building blocks of inexpensive industry-standard servers.

Virtual Infrastructure Benefits

VMware has made it possible to fully realize the enormous benefits of virtualization in production-scale IT environments by building virtual infrastructure automation and management capabilities around a best-in-class hypervisor. In fact, 86% of VMware customers use virtualization in production and 43% deploy most new production applications in virtual machines.

VMware virtual infrastructure solutions are ideal for production environments in part because they run on industry-standard servers and desktops and support a wide range of operating system and application environments, as well as networking and storage infrastructure. We designed our solutions to function independently of the hardware and operating system to provide customers with a broad platform choice. As a result, our solutions provide a key integration point for hardware and infrastructure management vendors to deliver differentiated value that can be applied uniformly across all application and operating system environments.

VMware customers who have adopted our virtual infrastructure solutions have reported dramatic results, including:

  • 60-80% utilization rates for x86 servers (up from 5-15% in non-virtualized PCs).
  • Cost savings of more than $3,000 annually for every workload virtualized.
  • Ability to provision new applications in minutes instead of days or weeks.
  • 85% improvement in recovery time from unplanned downtime.

Virtualization is a proven concept that was first developed in the 1960s to partition large, mainframe hardware. Today, computers based on x86 architecture are faced with the same problems of rigidity and underutilization that mainframes faced in the 1960s. VMware invented virtualization for the x86 platform in the 1990s to address underutilization and other issues, overcoming many challenges in the process.

Today, VMware is the global leader in x86 virtualization and has achieved success that is building momentum for virtualization in all x86 computers.

In the Beginning: Mainframe Virtualization

Virtualization was first implemented more than 30 years ago by IBM as a way to logically partition mainframe computers into separate virtual machines. These partitions allowed mainframes to “multitask”—run multiple applications and processes at the same time. Since mainframes were expensive resources at the time, they were designed for partitioning as a way to fully leverage the investment.

The Need for x86 Virtualization

Virtualization was effectively abandoned during the 1980s and 1990s when client-server applications and inexpensive x86 servers and desktops established the model of distributed computing. Rather than sharing resources centrally in the mainframe model, organizations used the low cost of distributed systems to build up islands of computing capacity. The broad adoption of Windows and the emergence of Linux as server operating systems in the 1990s established x86 servers as the industry standard. The growth in x86 server and desktop deployments has introduced new IT infrastructure and operational challenges. These challenges include:

  • Low Infrastructure Utilization—Typical x86 server deployments achieve an average utilization of only 10% to 15% of total capacity, according to International Data Corporation (IDC), a market research firm. Organizations typically run one application per server to avoid the risk of vulnerabilities in one application affecting the availability of another application on the same server.
  • Increasing Physical Infrastructure Costs—The operational costs to support growing physical infrastructure have steadily increased. Most computing infrastructure must remain operational at all times, resulting in power consumption, cooling, and facilities costs that do not vary with utilization levels.
  • Increasing IT Management Costs—As computing environments become more complex, the level of specialized education and experience required for infrastructure management personnel, and the associated costs of such personnel, have increased. Organizations spend disproportionate time and resources on manual tasks associated with server maintenance, and thus require more personnel to complete these tasks.
  • Insufficient Failover and Disaster Protection—Organizations are increasingly affected by the downtime of critical server applications and inaccessibility of critical end user desktops. The threat of security attacks, natural disasters, health pandemics and terrorism has elevated the importance of business continuity planning for both desktops and servers.
  • High Maintenance end-user Desktops—Managing and securing enterprise desktops present numerous challenges. Controlling a distributed desktop environment and enforcing management, access and security policies without impairing users’ ability to work effectively is complex and expensive. Numerous patches and upgrades must be continually applied to desktop environments to eliminate security vulnerabilities.

The VMware Solution: Full Virtualization of x86 Hardware

In 1999, VMware introduced virtualization to x86 systems to efficiently address many of these challenges and to transform x86 systems into general purpose, shared hardware infrastructure that offers full isolation, mobility, and operating system choice for application environments.

Challenges & Obstacles to x86 Virtualization

Unlike mainframes, x86 machines were not designed to support full virtualization, and VMware had to overcome formidable challenges to create virtual machines out of x86 computers.

The basic function of most CPUs, both in mainframes and in PCs, is to execute a sequence of stored instructions (ie, a software program). In x86 processors, there are 17 specific instructions that create problems when virtualized, causing the operating system to display a warning, terminate the application, or simply crash altogether. As a result, these 17 instructions were a significant obstacle to the initial implementation of virtualization on x86 computers.

To handle the problematic instructions in the x86 architecture, VMware developed an adaptive virtualization technique that “traps” these instructions as they are generated and converts them into safe instructions that can be virtualized, while allowing all other instructions to be executed without intervention. The result is a high-performance virtual machine that matches the host hardware and maintains total software compatibility. VMware pioneered this technique and is today the undisputed leader in virtualization technology.