Virtualization: Xen vs. Microsoft vs. VMware

Published on: February 13, 2007
Last Updated: February 13, 2007

Virtualization: Xen vs. Microsoft vs. VMware

Published on: February 13, 2007
Last Updated: February 13, 2007

Server virtualization has become a great tool for the data center, helped by the leading virtual server software vendors literally giving away their product.

And as more IT shops consolidate their servers using virtual machines (VMs), they find an active marketplace and plenty of choices for how to implement the concept.

Adoption of server virtualization is accelerating. According to a Forrester Research, survey 51 percent of enterprises are now using or piloting the technology.

It’s a powerful notion: take a single computer (a dual core or multi-processor CPU is best), and divvy it up into separate “virtual” machines with their own memory, virtual hardware and drive images, and other resources.

It isn’t new: IBM has been doing this on its mainframes for more than 30 years, and we’ve had blade servers for the past five years too.

But what is new is that the power of VM can be delivered to the PC platform, and there is a more compelling argument now that Microsoft’s Virtual PC and EMC’s VMware have free versions, along with pre-configured VMs to make setup even easier.

EMC offers this page with dozens of different “virtual appliances” that have already been configured for popular Web, database, and other applications servers. Just copy them and you’re ready to run something that could have taken hours or days to setup.

Microsoft even offers a virtual disk image that contains XP with Service Pack 2 and IE 6 for those shops that need to run IE 6 and 7 side-by-side. They also offer pre-built images of Exchange, SQL Server, and Windows Server 2003.

The idea is to run multiple operating systems and applications on the same box, making it easier to provision a new server and make more productive use of this hardware, just like our mainframe antecedents used to do in the 1980s.

But unlike the mainframe era, having multiple VMs means IT shops can cut the cost of software development and simplify configuration as they deploy new servers.

By eliminating the need for particular peripherals or supporting a particular graphics or network card, a VM set-up cuts the time to configure a new server.

And now that there is more power available on the PC platform, it makes a case for more consolidation.

“Two years ago, it wouldn’t have been possible to handle so much workload in a datacenter.

Now we can, thanks to this new virtualization software,” says Rene Wienholtz, the CTO of a Germany Web hosting provider called Strato that has deployed these technologies.

The key to successfully using VMs is to make them as cookie-cutter as possible, so that they can be quickly setup and cloned as new virtual servers are needed for the datacenter.

Comparing the alternatives

There are three major VM vendors currently, with others such as coming on strong too. EMC’s VMware has been around the longest and has the most complex product line, with both free and paid versions.

Microsoft purchased its line of virtual servers from Connectix and now offers the product for free, and has an open-source alternative that has both.

Before you choose your VM server vendor, here are some questions to ask to qualify the kind of product that will serve your needs best:

1) What Host Hardware And Operating System Will You Want To Run?

Each VM server product hosts its virtual machines in different ways. Some, such as the free VMware Server and Microsoft’s Virtual Server, run on top of ordinary Windows Server machines.

There is a difference, however: Microsoft requires a lot more than just the OS to run its virtual server product. you have to run the latest SPs and IIS and Active Directory and use IE. VMware needs just the basic OS. (More on that in a moment.)

VMware Server also runs on numerous Linux distributions, and Microsoft’s supports testing but not production use on XP Professional. Others, such as the paid VMware versions and Xensource, run on the “bare metal” of a PC – meaning that no OS is needed, and they install their own miniature OS to operate the various VMs.

These usually support the more recently higher-performance CPUs, but finding the right drivers to run these bare metal OSes may be an issue. It depends on what host OS you’re comfortable using in your enterprise and under what conditions.

2) What Guest OSes Do You Plan On Using?

Each VM product can run just about any “guest” OS but some are better tuned and pre-configured for particular OSes.

VMware has the widest support for many different Windows, Linux, and Unix OSes. Microsoft is of course more focused on their own Windows versions, and Xen supports some Windows and Linux versions and is adding more.

3) How Many VM Hosts Do You Plan On Operating And How Will You Manage Them?

Each virtual server solution has slightly different management tools and consoles to connect with the VMs that it is running.

Microsoft is the most closely tied to Windows and its own software such as Internet Information Server.

The management tool runs under IE v6 or later and you can view the console of each VM inside the browser frame.

They have another tool that is in beta (expected in the latter part of 2007) called System Center VM manager that will require Active Directory running on the host Windows Server 2003 machine.

Xensource’s Administrator Console runs on both Linux and Windows.

4) How Familiar Are You With Vm Concepts And How Important Is Support?

Part of operating VMs is having a solid base of support behind the products. VMware has been around the longest and has the best-developed reseller and support channel.

While Xensource is open source, the community is still pretty new and getting started.

If you have subscriptions to the various Microsoft TechNet and MSDN offerings you will have the resources to make use of its product.

5) What Is The Difference Between Free And Paid Products?

Each of the three major vendors offers free products: VMware Server, Microsoft’s Virtual Server, and XenExpress.

VMware offers three different paid versions of its Infrastructure line – Starter, Standard, and Enterprise, with corresponding price increases.

All three include the basic ESX software that runs the VMs, along with management tools.

The more expensive versions include support for server clustering and other high-availability options.

Xensource has two paid versions, XenServer and XenEnterprise. The former is licensed at $99 per year while the latter can be either licensed at $488 per year or purchased for a single fee of $750, so obviously for longer periods the purchase is the most cost-effective. The table below summarizes the various options for these three vendors.

Table: Virtual Server product comparison

Free server product VMware ServerVirtual Server 2005 R2XenExpress
Paid server productsInfrstructure v3 (Starter, Standard, and Enterprise)NoneXenServer and Enterprise
Pricing range paid product$1000 – $5750 (two CPU versions)FreeServer : $99/yr Enterprise: $750
Host OS (if any)Server:Windows Server 2003, various LinuxInfra v3:bare metalWindows Server 2003 SP1, XP Pro SP2 (for testing purposes only)Bare metal
Management toolsVirtual CenterVMotion migration toolSystem Center VM Manager (beta)Administrator Console
Support resourcesHighMediumMedium
AdvantagesWidest selection of pre-built appliancesWidest selection of guest OS supportWizards galore for install aidsCan run on any IE browser with Internet accessLess expensive optionEasy cloning of VM imagesOpen source solution that doesn’t require any host OS
DisadvantagesConfusing array of pricing and configuration optionsOnly four “virtual hard disk” pre-built appliances of MS server productsLimited hardware supportLimited Windows guest OS support

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Written by Bobby

Bobby Lawson is a seasoned technology writer with over a decade of experience in the industry. He has written extensively on topics such as cybersecurity, cloud computing, and data analytics. His articles have been featured in several prominent publications, and he is known for his ability to distill complex technical concepts into easily digestible content.