Other meanings of Virtualization
Computing
Virtualization is the creation of a virtual—rather than physical—version of a computing resource, such as a server, operating system, storage device, or network. It abstracts the underlying hardware, allowing multiple isolated environments to run on a single physical machine, which improves efficiency, flexibility, and cost-effectiveness. The concept dates to the 1960s with IBM's CP-40 and CP-67 systems, which pioneered time-sharing and virtual memory. Modern virtualization underpins cloud computing, enabling providers to offer scalable, on-demand resources. It is distinct from emulation, as virtualization typically runs code natively on the host processor, while emulation translates instructions for different architectures.
Virtualization abstracts physical hardware into logical resources, enabling multiple virtual machines (VMs) to share the same host. The hypervisor, or virtual machine monitor (VMM), is the software layer that manages these VMs, allocating CPU, memory, and I/O. There are two main hypervisor types: Type 1 (bare-metal) runs directly on hardware, as in VMware ESXi and Microsoft Hyper-V; Type 2 (hosted) runs on an existing operating system, like Oracle VirtualBox. Beyond server virtualization, other forms include desktop virtualization (VDI), storage virtualization (e.g., SAN pooling), network virtualization (e.g., VLANs and SDN), and application virtualization (e.g., Microsoft App-V). Each type isolates workloads, improving security and manageability.
The concept emerged in the 1960s at IBM, where CP-40 and CP-67 allowed multiple users to share a mainframe through time-sharing. In 1972, IBM's VM/370 commercialized virtual memory and full virtualization. The approach declined with the rise of cheap microcomputers but revived in the late 1990s when VMware introduced binary translation for x86, making virtualization practical on commodity hardware. In 2005–2006, Intel and AMD added hardware virtualization extensions (VT-x and AMD-V), eliminating the need for binary translation. This paved the way for cloud computing, as Amazon EC2 launched in 2006, leveraging Xen hypervisor to offer scalable virtual servers.
Virtualization is the foundation of cloud computing, enabling providers to multiplex physical servers among many tenants, reducing costs and energy consumption. It also supports disaster recovery through snapshots and live migration, as seen in VMware vMotion. Containers, such as Docker and Kubernetes, extend the concept by virtualizing the operating system rather than hardware, offering lighter-weight isolation. Virtualization enhances security by sandboxing applications and enabling micro-segmentation in networks. In data centers, it improves server utilization from ~10% to over 80%, according to industry reports. It also facilitates legacy system preservation, allowing old operating systems to run on modern hardware.
Virtualization has niche applications beyond servers. For example, IBM's z/VM supports hundreds of Linux VMs on a single mainframe, a practice still common in large enterprises. In the 1970s, the M44/44X project at IBM Research explored partial virtualization, influencing later designs. The term 'virtual machine' was coined by IBM engineer Robert Creasy in the 1960s. Virtualization also enables 'virtual appliances'—pre-configured VMs distributed as software appliances. In security, 'hypervisor-based rootkits' like SubVirt (2006) demonstrated how malware could hide beneath the OS. Additionally, 'hardware-assisted virtualization' is used in embedded systems for automotive and IoT, enabling mixed-criticality workloads on a single chip.
Virtualization continues to evolve with emerging technologies like unikernels and confidential computing, which isolate workloads in hardware-encrypted enclaves.
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