A hypervisor is a piece of computer software, firmware or hardware that creates and runs virtual machines. A hypervisor allows multiple operating systems to share a single hardware host. Each virtual machine has its own set of virtual hardware resources allocated to it, allowing the virtual machines to run independently as if they were physical computers.
Hypervisors are instrumental in hardware virtualization, enabling multiple virtual machines with heterogeneous operating systems to run in isolation on the same physical machine. This provides benefits such as server consolidation, improved disaster recovery and portability of virtual machines between hosts.
Hypervisors are classified into two types:
Type 1 Hypervisor
Also called bare metal hypervisor or native hypervisor, Type 1 hypervisors run directly on the system hardware. They have direct access to the underlying physical resources without requiring any operating system to work.
Some examples of Type 1 hypervisors include:
VMware ESXi: One of the most popular enterprise-grade bare metal hypervisors used in data centers for virtualization.
Microsoft Hyper-V: Created by Microsoft as a native hypervisor for virtualizing Windows and Linux systems.
Citrix XenServer: Open source bare metal hypervisor focused on server virtualization supporting Windows and Linux VMs.
Oracle VM Server: Type 1 hypervisor developed by Oracle that enables hardware virtualization.
Type 2 Hypervisor
Also known as hosted hypervisor, Type 2 hypervisors run as software applications on an underlying host operating system which provides virtualization services.
Some examples of Type 2 hypervisors include:
VMware Workstation: Developed by VMware for creating and running virtual machines on x86 and x64 personal computers.
Oracle VirtualBox: Popular open source, cross-platform virtualization software package allowing virtualization on desktop computers.
Windows Virtual PC: Virtualization program designed for Windows 7 and previous versions to run virtual machines.
Parallels Desktop: Commercial software for MacOS to run virtual machines with various operating systems including Windows, Linux and macOS.
The main difference between the two types of hypervisors is that Type 1 hypervisors interact directly with hardware while Type 2 hypervisors require a host operating system to access the underlying hardware resources
Type 1 hypervisors have better performance compared to Type 2 hypervisors since they don’t go through an intervening host OS. But Type 2 hypervisors are easier to install as regular software on existing user OS.
Key Advantages of Using Hypervisors
Hypervisors and hardware virtualization in general bring considerable benefits both from technological and business perspectives:
Increased hardware utilization: Allowing multiple VMs and workloads to share the same physical server leading to reduced infrastructure costs.
Isolation and security: Faults in one VM are contained from affecting other VMs or host system enhancing stability and security.
Portability: Virtual machines can be easily migrated between compatible hypervisor hosts.
Better disaster recovery: VMs can be backed up, replicated and restored easily for improved business continuity.
Testing and development flexibility: VMs can be quickly setup, reconfigured, cloned and discarded as required for testing software in different environments.
Consolidation and accessibility: Multiple operating systems can co-exist on the same hardware host and accessed remotely improving productivity.
Scalability: Scale up or down hardware resources allocated to VMs according to changing business needs.
As virtualized infrastructure becomes ubiquitous in IT, hypervisors continue to evolve quickly adopting new technologies like containerization and becoming more secure and optimized for diverse workloads including AI, ML, analytics and graphics. Leading companies like VMware, Microsoft, Red Hat and Nutanix offer hypervisors across different platforms tailored to customer infrastructure needs.
With forecasts predicting the global hypervisor market to reach $13 billion by 2030, hypervisors will undoubtedly keep enabling resource optimization through virtualization for the foreseeable future.
Hypervisors enable hardware virtualization by allowing multiple virtual machines (VMs) with heterogeneous operating systems to efficiently run on a single physical machine.
Type 1 (bare metal) hypervisors run directly on host hardware while Type 2 (hosted) hypervisors run on a host operating system.
Key benefits include increased hardware utilization, isolation, portability, disaster recovery and flexibility to test, develop, consolidate, scale and access multiple VMs.
Leading hypervisor vendors cater across different platforms helping customers realize the advantages of virtualization and containment offered by hypervisors.
Hypervisors are fundamental to hardware virtualization allowing enterprises to optimize infrastructure utilization while improving security and accessibility. With hyper-convergence, containers and hybrid cloud gaining momentum, hypervisors continue to adapt to emerging data center architectures and workloads.
While the hypervisor market outlook remains bullish as virtualization adoption grows, companies need to assess their platforms, capabilities and pricing models along with their specific IT environment and application needs. As leading vendors battle feature gaps and performance benchmarks, organizations stand to gain the most by aligning business goals with virtualization strategies leveraging different types of hypervisors.
Frequently Asked Questions
Q: What is a hypervisor?
A: A hypervisor is software, firmware or hardware that creates and runs virtual machines – allowing multiple operating systems to share a single hardware host efficiently.
Q: What are the main types of hypervisors?
A: Hypervisors are broadly classified into Type 1 (bare metal) which run directly on host hardware and Type 2 (hosted) which run on a host operating system.
Q: What is a Type 1 hypervisor?
A: Also called native or bare-metal hypervisor, a Type 1 hypervisor runs directly on the host’s hardware to control the hardware and manage guest operating systems. Eg. VMware vSphere ESXi, Microsoft Hyper-V, Citrix XenServer.
Q: What is a Type 2 hypervisor?
A: Also called hosted hypervisor, a Type 2 hypervisor runs as an application on the operating system of the host computer. Eg. Oracle VirtualBox, VMware Workstation, Parallels Desktop.
Q: What are the advantages of hypervisors?
A: Key advantages include increased hardware utilization, isolation and security, portability, disaster recovery, flexibility for testing and development, server consolidation and remote accessibility.
Q: What is hardware virtualization?
A: Hardware virtualization refers to the abstraction of logical computer resources such as CPU, memory, storage from their underlying physical resources – factorization made possible by a hypervisor.
Q: How are hypervisors being used?
A: Hypervisors are used widely across enterprises for server consolidation to optimize infrastructure utilization, reduce costs and enable rapid provisioning of VMs and workloads in data centers and cloud.
Q: Which hypervisor is the best for business?
A: The top hypervisor vendors include VMware vSphere, Microsoft Hyper-V, Citrix XenServer, Nutanix AHV and Red Hat Virtualization. The best hypervisor depends on your server OS, virtualization workloads, features and budgetary needs.
Q: What is VMware ESXi?
A: VMware vSphere ESXi is a very popular Type 1 enterprise-grade bare metal hypervisor OS from VMware used for virtualizing x86 servers to deploy and manage virtual machines and storage.
Q: How is a hypervisor different from an operating system?
A: Unlike an operating system, a hypervisor has no components for direct user interaction or access to physical hardware resources. Its primary task is virtualization – abstracting hardware and allocating resources optimally across virtual machines.
Q: Is Docker a hypervisor?
A: No, Docker is an open platform for building, deploying and managing software containers. Unlike a hypervisor which virtualizes hardware for guest operating systems, containers virtualize a computer’s OS to run isolated applications using the host system’s OS kernel.
Q: Can we run Docker inside a hypervisor?
A: Yes, Docker and hypervisors are complementary technologies. Docker containers can be run inside virtual machines created using hypervisors like vSphere, Hyper-V, KVM and VirtualBox to realize the combined benefits of both hardware and OS-level virtualization.
Q: What hardware resources do hypervisors virtualize?
A: Hypervisors virtualize physical server hardware resources like the CPU, RAM, disks and NICs (network interface controllers) to present a logical or virtual layer abstracted from the underlying real devices.
Q: How do hypervisors work?
A: A hypervisor runs directly on server hardware allocating appropriate CPU, memory, disk, network and I/O resources to efficiently run various guest operating systems and their applications in isolated, independent and portable virtual machines.