A hypervisor, also known as a Virtual Machine Monitor (VMM), is a crucial component of virtualization technology. It is responsible for creating and managing virtual machines (VMs) on a physical host machine. The hypervisor sits between the hardware and the operating systems or applications, providing a layer of abstraction that allows multiple VMs to share the same physical resources.
There are two main types of hypervisors:
- Type 1 Hypervisor (Bare-Metal Hypervisor):
- A Type 1 hypervisor runs directly on the physical hardware without the need for a host operating system. It has direct access to the underlying hardware resources.
- This type of hypervisor is considered more efficient and is often used in enterprise environments, data centers, and cloud computing platforms.
- Examples of Type 1 hypervisors include VMware ESXi, Microsoft Hyper-V Server, and KVM (Kernel-based Virtual Machine).
- Type 2 Hypervisor (Hosted Hypervisor):
- A Type 2 hypervisor runs on top of a host operating system. The host operating system manages the hardware, and the hypervisor operates as an application within that operating system.
- This type of hypervisor is commonly used for development, testing, and desktop virtualization scenarios.
- Examples of Type 2 hypervisors include VMware Workstation, Oracle VM VirtualBox, and Microsoft Hyper-V (when installed on a Windows operating system).
Key functions of a hypervisor include:
- Virtual Machine Creation:
- The hypervisor creates and manages multiple virtual machines on a single physical host. Each VM operates as an independent instance of an operating system.
- Resource Allocation:
- The hypervisor allocates physical resources, such as CPU, memory, and storage, to each virtual machine based on its configuration and demand.
- Isolation:
- VMs are isolated from each other, preventing interference and providing security. Failures or issues in one VM typically do not affect others.
- Hardware Abstraction:
- The hypervisor abstracts the underlying hardware, presenting a virtualized view to each VM. This allows VMs to run different operating systems and applications on the same physical hardware.
- Live Migration:
- Many hypervisors support live migration, allowing VMs to be moved from one physical host to another without disruption. This is useful for load balancing, maintenance, and improving resource utilization.
- Snapshot and Backup:
- Hypervisors often provide features for creating snapshots and backups of virtual machines, enabling quick recovery and ensuring data integrity.
Hypervisors play a crucial role in server virtualization, cloud computing, and other virtualization scenarios by enabling efficient resource utilization and flexibility in managing computing resources.
