virtual machine (VM)

What is a Virtual Machine (VM)?

A Virtual Machine (VM) is a software-based environment that acts like a separate computer with its own CPU, memory, storage, and network interface, created from a pool of hardware resources. It operates within a physical machine, known as the host, while the VMs are referred to as guests. This setup is managed by a hypervisor, software that isolates and allocates resources from the host to each VM, allowing multiple operating systems to run simultaneously on one machine. For example, you can run a Linux distribution alongside MacOS or Windows on the same computer.

Understanding Virtualization

Virtualization technology leverages hardware resources traditionally bound to specific functions, allowing them to be distributed among multiple users or environments. This increases the efficiency of a physical machine by maximizing its resource utilization. Different types of virtualization include:

• Data Virtualization: Combines data from various sources into one dynamic system.
• Desktop Virtualization: Centralizes and manages multiple simulated desktop environments.
• Server Virtualization: Partitions servers for specific tasks or functions.
• Operating System Virtualization: Runs multiple operating systems on a single machine.
• Network Functions Virtualization: Distributes network services like file sharing or IP configuration across environments.

How Does a Hypervisor Work?

A hypervisor manages the hardware and virtual environments by separating the physical resources for the VMs. It schedules and allocates resources like CPU and memory from the physical machine to the virtual machines. In Linux, the Kernel-based Virtual Machine (KVM) is a built-in hypervisor, while other options include Xen and Microsoft Hyper-V.

There are two types of hypervisors:

1. Type 1 (Bare Metal): Runs directly on the physical hardware, with VMs accessing resources directly. KVM is an example.
2. Type 2 (Hosted): Runs on top of a host operating system, which manages resource allocation. Examples include VMware Workstation and Oracle VirtualBox.

Advantages of Virtual Machines

• Multi-OS support: VMs enable running multiple operating systems on a single machine, unlike traditional setups where one OS runs on one machine.
• Server consolidation: By virtualizing servers, you can host several virtual servers on one physical machine, leading to better hardware utilization and cost savings.
• Resource optimization: Virtualization reduces the need for extra physical resources like hard drives, and cuts down on power, space, and cooling requirements in datacenters.
• Disaster recovery: VMs offer more flexible disaster recovery solutions, such as failover and redundancy, without needing extra hardware.
• Testing environments: VMs are ideal for testing applications or creating production environments in isolation from other systems.

How VMs Enable Cloud Computing

Virtualization is a core technology that enables cloud computing. Cloud platforms virtualize resources into shared pools, adding layers of control and automation. Virtualization software, alongside management and automation tools, connects physical resources, virtual data, and end-users in the cloud, providing flexible and scalable computing solutions.