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There’s nothing more likely to get a VMwarite riled up than comparing Microsoft Virtual Server (MSVS) and VMware ESX Server. Although they both virtualize an x86 system, MSVS runs on top of Windows, and ESX Server doesn’t. VMware does have a server product that runs on top of a host operating system like MSVS, and it’s the free VMware Server. MSVS should by all rights be compared to VMware Server, not ESX Server. ESX Server is much more powerful, but comes at a higher price, a bit more complexity for enterprise-scale deployments, and a smaller universe of supported hardware.

So let’s look at this article by the usually excellent Alex Barrett at the usually excellent SearchServerVirtualization. It starts with a fair premise — for some small shops, it’s a path of least resistance to just use MSVS and call it a day. And when you read closely, Alex mentions VMware Server, but when the people he interviews start talking about price and VMotion in an article on MSVS, my alarm bells go off.

Microsoft Virtual Server flawed, not broken, users say.

That’s fairly typical of most small shops, said Chris Wolf, senior analyst with the Burton Group and author of Virtualization: From the Desktop to the Enterprise. "If [you] have just a few test systems, you’re not going to see much of a difference in performance," he said, between MSVS and VMware. But systems that start to max out their physical RAM might not get the performance from MSVS that they would with VMware, whose memory management feature moves underutilized memory to the hard disk, freeing up RAM for other busy virtual machines.

I think he’s talking about ESX Server’s balloon memory driver, which along with shared memory pages does help use memory more effectively between multiple virtual machines … for ESX Server, not VMware Server. Also note how he compares "MSVS" (a product) and "VMware" (a company name, but he means ESX Server).

But the performance kick he gets from VMware does come at a price:
having to learn an unfamiliar new operating system. "I wish I were more
of a Linux person," Laudenslager said about having to administer his
Linux-based VMware Server. Especially when it comes to setting up
security policies, "I feel I could do a better job with Windows."

Laudenslager should be running VMware Server on Windows, not Linux, if he’s a Windows person. VMware Server comes in both flavors.

Then, there are a few things that MSVS flat out does better than
VMware. Hardware compatibility, for one thing, said Anil Desai, an
independent consultant in Austin, Texas. VMware has done a good job
expanding an extensive hardware compatibility list, but it can’t
compare with the 20,000 to 30,000 devices supported by MSVS’s
underlying Windows Server 2003 platform, Desai said.

Again, if you run VMware Server on Windows, you get to take advantage of all the device compatibility of Windows 2003, the same as MSVS does. It’s when you move up to the power of ESX Server that you start having to be more careful about hardware compatibility.

If you buy contemporary hardware from tier-one OEMs, hardware
compatibility shouldn’t be much of an issue for most VMware shops, said
Andrew Kutz, an operating systems specialist for the University of
Texas, which runs VMware. But, "if you’re a white box shop that builds
all your own stuff, you’re going to run in to some problems," he said.

And now I sound like a broken record — use VMware Server on Linux or Windows on your white box all day long. Go to the VMware Forums if you’re hardware savvy and you can probably even get ESX Server up on unsupported hardware for your lab, although we don’t recommend it for production. But great googly moogly, don’t go saying VMware doesn’t have a free product to run on that cheapo white box you just bought — just use VMware Server!

Is it sour grapes to complain about an article that calls your competitor’s product "flawed" in the title? I see this mistaken comparison so often, maybe I should start a new "apples to oranges" category in the blog for all these sightings. Of course, they’ll go away as soon as Microsoft’s upcoming Viridian hypervisor is here (2008? 2009? Infinity + 1?), and they strangle MSVS and dump it in a back alley. In the meantime, I guess VMware has some more marketing to do, since VMware Server is a great solution to pop on top of Windows Server and get started virtualizing — no cost, no  Linux, and it runs just fine on your current hardware.

–jtroyer