A virtual machine (VM) is a software-based computer that emulates the functionalities of a physical computer. It simulates a complete hardware environment, including CPU, memory, network interfaces, and storage space, but allows execution on a physical host system. VMs offer the possibility to run multiple operating systems simultaneously on a single hardware. This optimizes resource utilization and increases flexibility in IT infrastructure.
How does a virtual machine work?
A VM works by running a guest operating system in an isolated environment. This isolation ensures that the guest operating system and its applications operate independently from the host system. This allows different operating systems, such as Windows, Linux, or macOS, to run in parallel on the same physical computer without interfering with each other.
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A significant advantage of virtual machines is their flexibility. Companies can divide a single physical server into multiple VMs, thus running different applications or services on a single hardware. This leads to cost savings, as fewer physical servers are needed. Additionally, the efficiency of resource utilization improves as the hardware is better utilized.
Categories of virtual machines
Virtual machines are often divided into two main categories: system-based and process-based VMs.
- System-based VMs, also known as hypervisor-based VMs, virtualize the entire hardware and allow running multiple guest operating systems. This type of VM is primarily used in data centers to optimize server resources.
- Process-based VMs, on the other hand, focus on executing individual applications and provide a platform-independent runtime environment. A well-known example of this is the Java Virtual Machine (JVM), which allows Java programs to run on various devices regardless of the underlying hardware.
VMs and Hypervisors
A crucial element of virtualization is the hypervisor, a software that manages the VMs. There are two main types of hypervisors: Type 1 hypervisors, which run directly on the host system’s hardware, and Type 2 hypervisors, which operate within a host operating system. Type 1 hypervisors offer higher performance and security as they interact directly with the hardware. Type 2 hypervisors, on the other hand, are easier to implement and ideal for development environments.
