A hypervisor (also known as a Virtual Machine Monitor (VMM)) is software that enables virtualization. It creates and manages virtual machines (VMs) on a physical computer, acting as an abstraction layer between the hardware and one or more operating systems.
A hypervisor can be compared to a conductor in an orchestra. It ensures that all instruments (in this case, virtual machines) use their resources effectively and do not interfere with one another. A hypervisor’s primary task is resource allocation. It distributes hardware resources such as CPU time, storage space, and network capacity so that each virtual machine operates as if it had its own dedicated hardware. A hypervisor enables a computer to run multiple operating systems simultaneously, as if they were installed on separate machines.
Type 1: Type 1 hypervisors run directly on the bare hardware of the host system. They are also known as bare-metal hypervisors. Examples include VMware ESXi, Microsoft Hyper-V, and Xen. As a rule, they offer better performance and higher security because they operate directly on the hardware.
Type 2: Type 2 runs within a host operating system. It is considered a “hosted” hypervisor and is particularly suitable for test environments or developers. Well-known examples include VMware Workstation and Oracle VirtualBox. These hypervisors are more flexible and easier to set up because they are installed on an existing operating system like any other software.
Well-known hypervisor products include VMware vSphere (ESXi), which is widely used in large IT environments. Following the announcement of the acquisition by Broadcom, concerns were raised about future developments and support strategies, as Broadcom’s previous acquisitions have often led to changes in product maintenance. In VMware’s case, licensing in particular was criticized. Microsoft Hyper-V is a component of Windows Server and is often used in environments based on Microsoft technologies. Citrix XenServer is an open-source hypervisor known for its high performance and scalability, and is used especially in cloud computing. KVM (Kernel-based Virtual Machine) is part of the Linux kernel and offers a cost-effective solution for Linux-based environments. Oracle VM Server specializes in optimizing Oracle applications and databases.
When selecting a hypervisor, you should consider compatibility, performance requirements, management tools, security features, and cost. Enterprise hypervisors offer comprehensive support services and advanced features, while open-source hypervisors provide greater flexibility and customization options at lower cost.
