Server virtualization is a critical data center technology, but it can be a costly one. The key to success is to deploy and manage virtualization cost-effectively enough to reap its benefits in cost savings on power, cooling, building space, maintenance costs and hardware purchases and upgrades. Fortunately, free tools are available to help IT managers to unlock the door to success.
In this two-part tip, I'll discuss the features and merits of the most popular free virtualization platforms, security and monitoring solutions.
My goal is to help companies who believe in this technology's benefits, but have been discouraged by what can be a too long-term return on investment. After all, adopters often make high initial investments in new class of hardware, like Storage Area Networks (SANs); on software and hardware redundancy, on more rational provisioning procedures; and on training. The latter is greatly needed because virtualization is not something you can implement without a solid knowledge of operating systems, storage, networking, security, performances troubleshooting. Fortunately, broad availability of free tools creates an opportunity for companies to start small projects in a reliable way.
VMware Server and VMware Player
First of all, we need a virtualization engine. Here we really have the biggest opportunity to save money. VMware is master of free virtualization platforms with its Server and Player, in my opinion.
VMware Server used to be an enterprise virtualization platform called GSX Server with impressive features and management capabilities for Windows and Linux operating systems.
At the end of 2005, VMware decided to release it for free, without any form of limitation, conquering a big SMB market share.
VMware Server offers first-class features like support for 32- and 64-bit operating systems (including multiple editions of Windows, Linux and Solaris); up to two virtual CPUs and 3-6 GB RAM per virtual machine; capability to save virtual machine state; scripting APIs; Web and rich-client management tools; and much more.
Just five months after the launch of Server, VMware announced a second free platform: VMware Player.
Player is feature-limited edition of another popular VMware product called Workstation. It's able to run just one virtual machine per time, without virtual hardware editing capabilities; the latter is easily circumvented with free and allowed third-party tools like EasyVMX.
Server and Player can read each other's virtual machines, so that VMware users can create and test them on Server, and then distribute to customers, sales force, partners, etc.
Microsoft Virtual Server 2005 R2
VMware has not been alone in this liberal effort: Microsoft followed the trend and started offering its Virtual Server 2005 R2 for free.
Virtual Server comes from Microsoft's acquisition of Connectix in 2003, and it used to be a commercial solution available in Standard and Enterprise edition. The market dominance fight with VMware led to the re-release of the highest-end version of this product for free in April 2006.
In the not-so-far future, Microsoft could do much more than offer a free alternative to VMware Server: Its next generation virtualization engine, Windows Server Virtualization (codenamed "Viridian" at time of publication), is expected somewhere in the middle of 2008. The software giant is slated to offer it for free.
If so, every company on the planet deploying a new Windows Server machine will be able to start earning virtualization benefits immediately, as an out-of-the-box experience.
Free virtualization platforms include Xen, initially developed at Cambridge University, and now a project involving major IT vendors, like IBM, Novell, Red Hat and many others.
Xen is an open source project distributed under GPL license, so it's available for free to anybody willing to download sources and install them on a Linux operating system.
Xen is still behind in capabilities and usability offered by VMware and Microsoft solutions, but two companies are working to fill the gap: XenSource and Virtual Iron.
Both vendors are offering their own enhancements on top of Xen, improving performances or management capabilities, and both offers scaled down versions of their products for free.
XenSource exposes XenExpress, able to run up to four concurrent virtual machines (on a maximum of two physical sockets) each with up to 4 GB RAM, while Virtual Iron offers a Single Server Edition without any limitations.
The most unexpected free virtualization engine is Linux. The open source operating system itself is able to act as virtualization platform in a few months, thanks to the inclusion of KVM. KVM is still very young and not comparable with any product above, but the idea of having an out-of-the-box virtualization solution has already attracted a lot of community members and IT vendors, such as Red Hat, which are endorsing the solution.
Any kernel beginning with version 2.6.21 includes KVM, so any Linux distribution based on this kernel will be able to serve as a free virtualization platform.
Another project made its way on the Linux platform: OpenVZ, the open source edition of SWsoft Virtuozzo.
OpenVZ, just like Virtuozzo, has a different approach than the hardware virtualization solutions mentioned so far. Others were able to create isolated containers where users can install any kind of operating system -- like a Windows virtual machine on top of a Linux platform -- but OpenVZ is "only" able to create isolated containers with copies of the same operating system. This approach is less flexible but more suitable for some virtualization projects, like virtual hosting environments built by ISPs.
Moving away from Windows and Linux, I've found that even Sun is offering a virtualization technology for free. It's named Solaris Containers -- also called Zones -- and is included in the Sun Solaris 10 operating system, which is free for personal and commercial use.
Solaris Containers currently use the same approach as OpenVZ -- creation of multiples Solaris partitions isolated from each other -- but there's a hitch: Sun has been working on a new version for two years that is able to run also Linux binaries without any modification. We're still waiting for that.
At the end of this long list, which is far from complete, one conclusion is very apparent: Virtualization is becoming a commodity, and all operating systems will eventually offer virtual machines as a standard feature.
Companies wanting to utilize virtualization technology now have a great opportunity to adopt virtualization without spending extra money on corporate-edition software.
About the author: Alessandro Perilli, a self-described server virtualization evangelist, launched his influential virtualization.info blog in 2003. He is a Microsoft Most Valuable Professional for security technologies and the certifications he holds include Certified Information Systems Security Professional; Microsoft Certified Trainer; Microsoft Certified System Engineer with Security competency; CompTIA Linux+; Check Point Certified Security Instructor; Check Point Certified System Expert+; Cisco Certified Network Associate; Citrix Metaframe XP Certified Administrator.