Virtual Machine Options

As Virtualisation makes it relatively easy to setup a large number of systems, it can help you configure a large number of systems. Each dedicated to a specific service. To that end, it can be separated into 5 different categories.

• Application Level
• Platform-level VMs
• Paravirtualization
• Hardware-assisted Virtualisation
• Bare-metal Virtualisation

Application Level

Systems like WINE are application level virtualisations. They allow the installation of a single application that were designed to be run on an entirely different system.

Platform-level VMs

Applications such as VirtualBox or VMware Player are platform-level VMs. They emulate systems to allow for contained systems to have their own hardware that systems can be installed against.

Paravirtualization

While similar to Platform-level VMs, they work with fewer resources and usually require a specialised kernel such as Xen.

Hardware-assisted Virtualisation

A hardware interface where VMs have access to hardware features of the CPU such as VMX/SVM flags on Intel/AMD chips respectively.

Bare-metal Virtualisation

Some VM systems include a minimal operating system dedicated to VM operation. Two examples of this are Citrix XenServer and VMware ESX.

Notes

The KVM solution that comes with RHEL6 is known as hypervisor, a VM monitor that supports the running of multiple operating systems concurrently on the same CPU. KVM replaces the previous default of Xen.

KVM has replaced Xen in many open-source operating systems. XenSource which is owned by Citrix started working with Microsoft after RHEL5 was released.