Virtualization Home
Virtualization Overview
Virtualization and Virtual Machines Introduction
At the most basic level, Virtual Machine (VM) technology allows you to exploit the true power and flexibility of your server, desktop, or laptop computing hardware and reduce hardware costs by 50% or more by running multiple operating systems simultaneously on a single computer. With modern Processors / CPUs (like those offered by Intel), coupled with leading-edge virtualization software from VMware, you will be amazed at how efficiently and transparently you emulate "multiple machines" on one computer.
Mainstream Virtual Machine technology is one of the most exciting technological advancements in computing in recent years. We deploy solutions that make use of VMware ESXi "bare iron" (i.e., no Operating System required on host machine) hypervisors and embedded Virtual Machine technology.
In addition, we highly recommend VMware Workstation for everyday desktop use, especially if you are a software developer or run multiple operating systems. When coupled with high-performance, high-efficiency computing hardware (CPUs, storage solutions, and the like), Virtualization can save you a fortune and increase your productivity substantially!
Hosted vs. Bare-Metal Virtualization
There are two common approaches to virtualization: "hosted" and "bare-metal" (in the above diagram, "hosted" virtualization is depicted in the leftmost image, and a bare-iron/bare-metal virtualization paradigm is pictured to the right. Hosted virtualization software, like VMware Workstation or VirtualBox, runs as an application or "guest" on top of a general-purpose operating system (e.g., Windows XP, Windows Vista, Windows Server 2003 or 2008, Linux, etc). Bare-metal virtualization, like VMware ESX / ESXi, interfaces directly with computer hardware, without the need for a host operating system.
So, which type of virtualization best fits your requirements? This can be a rather complicated decision making process as you weigh the advantages and disadvantage, or "pros and cons", of bare-iron vs. hosted virtualization.
Each solution allows you to run multiple operating systems simultaneously on the same computer (e.g., Linux, Windows XP, Windows Vista), as well as the applications specific to each operating system. Here are some common things to consider:
- One substantial consideration when selecting a virtual solution is what hardware devices (i.e., system devices) the virtualization software will recognize, support, and allow the various hosted virtual machines access to. If you require access to USB devices, like USB printers, scanners, flash drives, cameras, and other USB devices that are typically considered "plug and play" these days, chances are rather good that you will want to implement a hosted solution in order to gain access to those devices.
- Currently, a bare-iron virtual solution like VMware ESXi does not support / allow the hosted virtual machines to access USB devices. By contrast, VMware Workstation 6.5 and 7.x have rather robust support for such devices and pass-through (to guest machines) support. UPDATE — JUNE, 2011: the upcoming VMware ESX / ESXi version 5.0 is rumored to include support for host machines to access USB devices. See this blog about VMware ESXi 5.0 Release Features of Interest for more feature previews.
- In general, if your guest machines are to run applications that require hardware-accelerated graphics or otherwise require high-resolution, again the chances are that you do not want a bare-iron solution. E.g., with the current VMware ESXi remote-console (in VMware Infrastructure Client) guest screen displays with video resolutions beyond 1180x885 are not supported with their SVGA driver.
- UPDATE — JULY, 2009: with the new VMware ESX / ESXi version 4.0, this limitation has gone away, and we have been running extremely high screen resolutions with ESXi and the accompanying vSphere client with great satisfaction and no speed or screen-refresh issues (at resolutions of 1920x1200 or greater!) There are also other ways (in addition to remote-console) to access a hosted ESXi virtual machine over the network, but do not expect anywhere near native screen refresh performance with a VNC Client or the like.
- Some bare-iron virtualization options, like VMware's free ESXi product, require remote management to perform anything more than the basic configuration operations. In the case of ESXi, VMware offers their VMware Infrastructure Client that provides rather comprehensive graphical administration functionality.
- Even with the remote GUI, under ESXi your options for system backup and other administrations may be limited without add-on products (especially referring to the FREE ESXi version that does not include the integrated consolidated system backup utility as part of that free package).
We have additional information throughout our website to help you make a more informed decision: