Hypervisors: KVM, Xen, VMware, Hyper-V

There are four major hypervisors - KVM, Xen, VMware and Hyper-V. The following is a snapshot of these hypervisors. (I hope I can add more details for each of them later).

KVM – a Linux based open source hypervisor. First introduced into the Linux kernel in February 2007, it is now a mature hypervisor and is probably the most widely deployed open source hypervisor in an open source environment. KVM is used in products such as Redhat Enterprise Virtualization (RHEV).

 KVM creates virtual machines as Linux processes.

Xen – An open source hypervisor which originated in a 2003 Cambridge University research project. It runs on Linux (though being a Type 1 hypervisor, more properly one might say that its dom0 host runs on Linux, which in turn runs on Xen). It was originally supported by XenSource Inc, which was acquired by Citrix Inc in 2007. 

VMware's ESXi – vSphere uses VMware’s ESXi hypervisor. VMware’s hypervisor is very mature and extremely stable.

Hyper-V – Hyper-V is a commercial hypervisor provided by Microsoft. Whilst excellent for running Windows, being a hypervisor it will run any operating system supported by the hardware platform. MS's public cloud Azure is based on hyper-V technology.