Types of Hypervisors
Type 1 Hypervisor
Type 1 hypervisors are also known as bare metal hypervisors because they run directly on the hardware of the host machine. This type of hypervisor replaces the standard operating system that would normally be installed on the hardware to allow for the hosting of multiple operating systems.
This type of hypervisor is normally used by enterprise data centers and by cloud computing providers. There are a few reasons why type 1 hypervisors work better than type 2 hypervisors in certain environments:
- They interact directly with the hardware instead of through an extra operating system layer, allowing for more efficient use of resources
- They allow for over-allocation of physical resources, assigning more resources than actually available to guest machines, but only allocating what the guests can actually use
- They allow for easy disaster recovery because if one machine fails, guests can be moved quickly to working hardware
Type 1 hypervisor software includes KVM, Microsoft Hyper-V, and VMware vSphere. All Linux kernels after 2007 include KVM which means modern Linux distributions contain a built-in type 1 hypervisor.
Type 2 Hypervisor
This type of hypervisor runs as an application on top of an operating system and is also called a hosted hypervisor. It abstracts the guest operating systems from the host operating system and allows guests to access resources on the machine through the operating system instead of directly.
Type 2 hypervisors are usually found in environments that need a smaller number of virtual machines because they aren't as efficient as a type 1 hypervisor. Here are some reasons you might use a type 2 hypervisor instead of a type 1 hypervisor:
- They are much easier to set up and manage because they act like any other application on an operating system
- They are compatible with a wide range of hardware because they work through the operating system
- They don't require an admin to manage
Type 2 hypervisor software includes VMware Workstation, Parallels Desktop, and Oracle VirtualBox.