What is Type-1 Hypervisor?

Type 1 hypervisors are an OS themselves, a very basic one on top of which you can run virtual machines.

One of the best features of type-1 hypervisors is that they allow for over-allocation of physical resources.

With type 1 hypervisors, you can assign more resources to your virtual machines than you have available. For example, if you have 128GB of RAM on your server and eight virtual machines, you can assign 24GB of RAM to each of them. This totals to 192GB of RAM, but VMs themselves will not actually consume all 24GB from the physical server. The VMs think they have 24GB when in reality they only use the amount of RAM they need to perform particular tasks.

Unlike Kubernetes cluster where you define the resource limit of pods which is then deducted from the cluster’s capacity even if you use a minuscule amount of it.

Vendors: KVM, VMware vSphere, Microsoft Hyper-V, Citrix Hypervisor

What is Type-2 Hypervisor?

As opposed to type-1 hypervisors that run directly on the hardware, hosted hypervisors or type-2 hypervisors have one software layer underneath.

A type 2 hypervisor occupies whatever you allocate to a virtual machine.

When you assign 8GB of RAM to a VM, that amount will be taken up even if the VM is using only a fraction of it.

If the host machine has 32GB of RAM and you create 3 VMs with 8GB each, you are left with 8GB of RAM to keep the physical machine running. Creating another VM with 8GB of RAM would bring down your system. This is critical to keep in mind, so as to avoid over-allocating resources and crashing the host machine.

Vendors: VMware Workstation, Oracle VM Virtualbox, Windows Virtual PC

#baremetal #virtual-machine #devops #cloud #vm