More on Virtualization
Posted on July 5, 2006
Filed Under Open Source/Freeware, Software |
In my last column I touched on virtual computers and servers as well as their unique benefits. Virtual Computers or Virtual Machines (VMs) run entirely in software and permit any number of different operating systems to run on a single computer.
The only limits to that are the physical resources available to the VMs. The more power the physical computer has, the more VMs you can run on it.
Because VMs run entirely in software, their configurations, operating system, and the data they contain are all stored in regular computer files. VMs are also for the most part independent of the hardware they run on since the virtualization software itself acts as a middleman between the hardware and virtual machine.
Those two points have major implications when hardware failures or upgrades are considered. Because a VM’s configuration and contents are stored in files and physical hardware is of little to no concern, VMs can be moved from computer to computer with ease. Upgrading to a new computer or server or even replacing a broken one can be as simple as installing the virtualization software on the new hardware and copying the virtual machines to it.
Because more than one operating system can run on a single computer, virtual machines can be employed to consolidate servers. Consolidated servers can obviously be cost effective but there are also savings to be had in power consumption. Fewer computers use less energy and also generate less heat. Server rooms thereby require less air conditioning.
Given that there are free virtualization options available (more on that in a bit) there are opportunities for even small businesses or home users to benefit from the technology.
As a Microsoft Small Business Specialist I’ve come to appreciate the features and price point of MS Small Business Server 2003. Microsoft Exchange is included with the server and among other things it is a full fledged email server. Exchange suffers from a lack of a low cost and effective SPAM filter however.
Virtual servers solve this problem nicely. Spamassassin is considered one of the better SPAM filters out there and while there are ways to make it run on Windows, Spamassassin is UNIX based software.
While most small businesses can’t justify the cost of an additional server to run Spamassassin, it is very cost effective to run some type of UNIX with Spamassassin in a virtual machine directly on the Small Business Server. In this way email can be filtered through Spamassassin and then delivered to the Exchange server.
Currently there are three major players in the virtualization arena. Interestingly all three players are offering free versions of their software and one player, Xen, is completely open source.
VMware (www.vmware.com) has been in the virtualization business for years and is the company most people think of when they think of virtualization. With a mature and solid line of products, VWware comes in the free Player and Server versions as well as Enterprise versions.
Notable about VMware aside from it’s longevity in the market, is that the Enterprise versions are operating systems in and of themselves. The Microsoft and Xen offerings run on Windows and Linux respectively where VMware Enterprise installs directly onto a bare hard drive. The VMware Enterprise operating system provides the foundation for other operating systems to run and does not require a host itself.
Microsoft is fairly new to the virtualization game and currently has two offerings. Microsoft Virtual PC 2005 retails for $129 US and will run on Windows XP or 2000 Professional or Windows XP Tablet PC Edition. Microsoft Virtual Server is a free add-on to Windows Server 2003 and can be downloaded from http://www.microsoft.com/windowsserversystem/virtualserver/downloads/default.mspx
Xen (www.xensource.com) is an open source product that is freely available to download, install, and modify. Xen runs on Linux and unlike Microsoft and VMware, can be quite complex to install and configure. Currently Xen also supports a limited number of guest operating systems.
While virtualization has been around since the 70’s, it has in the past few years been making waves as hardware has become more powerful and the need for multiple systems has increased. Virtualization is on the verge of revolutionizing how we manage computer systems.
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