Bare metal refers to the server system hardware without any OS or other software installed on it. HypervisorĪ hypervisor is a bare metal approach to virtualization. VirtualBox is best suited for small networks and individuals for the same reasons as VMware Server. With adjustable video memory, remote device connectivity, RDP connectivity, and snappy performance, it may well be the best hosted virtualization package in your arsenal. Like VMware Server, it is free and cross-platform, but unlike VMware Server, it is open source. VirtualBox, which is now Sun xVM VirtualBox, is one of my favorite virtualization packages. VMware Server supports 64-bit machines as hosts and guests. It has limited usefulness in large environments because of its memory limitations for VMs and sluggish disk performance. It is a free offering from VMware and is considered an introductory package for use in small environments, testing, or for individuals. VMware Server is used throughout this book to illustrate virtualization techniques and technologies. Therefore, we tell those who use hosted virtualization to interact with their VMs over the network using Windows Terminal Services (RDP) for Windows VMs or SSH for Unix and Linux systems. Nondisk operation speed, however, is near native. The major disadvantage is that disk I/O suffers greatly in this particular technology. Each VM (guest) possesses a consistent set of hardware.

The greatest advantage of this kind of virtualization is that there are a limited number of devices and drivers to contend with. They are also not aware of other guests on the system unless it's via another guest's network services. Guests assume they are standalone systems with their own hardware. Guest systems are fully virtualized in this scenario and have no knowledge of their virtual status. VMs are centrally managed by a host application that sees and manages each VM as a separate application. Guests usually consist of one or more virtual disk files and a VM definition file.

Os x virtualization on linux