Let's first take a look at the negative aspects of running VMware Server on Windows. The first area we will look at is cost. VMware Server does not support Windows XP; this means that you need a server license for Windows Server 2003 to run VMware Server with Windows. Windows Server 2003 is currently retailing for around $1,200 on NewEgg.com. Strike one -- the free server virtualization platform from VMware is not exactly free on Windows.
Windows also has inconsistent marks in its track record when it comes to security. One report says this, and another says that. The fact of the matter is that I manage both Windows and Linux servers, and I have to install far more patches on the Windows servers than I do for their Linux brethren. Out of the box, Linux simply trounces Windows when it comes to pre-configured security.
That is not to say that a Windows server cannot be made secure. In fact, a well configured Windows server is much easier to manage than a Linux server (in my personal opinion), but the fact remains that if you install one server with Windows and the next with Linux, put them both on the network and then leave the room, the Windows box will be the one getting pwned.
The last negative aspect we will look at for hosting VMwareServer on Windows is the overhead of the host operating system. Windows has a higher constant overhead than Linux because of all of the unnecessary services that are turned on by default in Windows, not to mention its graphical user interface (GUI).
Of course, disabling unneeded services in Windows can minimize the host OS overhead, but it is not possible to turn off the GUI (Microsoft says a no-GUI option is coming in Longhorn, the "enterprise" option, but this is misleading -- there is still a graphical logon prompt; it just opens up cmd.exe as the shell instead of explorer.exe). If the server you are planning to install VMware Server on does not have enough resources to share with the host OS and the VMs, it is best to use Linux as the host OS, because a Windows host OS will want more than its fair share of physical resources.
Running VMware Server on Linux has cons as well, to be fair. The first demerit is that, unlike Windows, VMware Server on Linux does not include the easy-to-use graphical VM networking configuration tool. You may be thinking to yourself, "Hey, he just finished saying the need for a GUI was a negative against Windows. This doesn't make sense!?" True, but with ncurses it is possible to write a simple graphical program for the command line. If you have to manage VM networks in both Windows and Linux, you'll quickly find yourself missing the tools when you are in Linux.
The second strike against VMware Server on Linux is that it requires a separate Apache installation for its Management User Interface (MUI). I spend a lot of time making sure my IIS and Apache Web servers are as secure as they can be, and it is very annoying that Linux VMware Server MUI cannot use my existing Apache installation. I am sure VMware does this so that they can easily issue patches and such -- closed loop software, but I inevitably customize parts of their Apache install anyway. I would like to see the MUI installation creating a single include file that I can link into my normal Apache install. Until this happens, running a second Web server is a negative in my book.
Finally, perhaps the most annoying thing about hosting VMware Server on Linux is kernel updates. Any significant update to the Linux kernel will require you to reconfigure VMware Server. This is not a hard thing to do, but it is easily forgettable and can lead to huge downtime if it is forgotten. If VMware Server detects a kernel update, it should silently reconfigure itself so that it can load in the running kernel.
On to happier topics. The biggest reason to host VMware Server on Windows is the host operating system's manageability. When joined to an Active Directory, Windows can take advantage of centrally managed domain accounts, group policy, SMS and many other must-have features for controlling large pools of servers. The stand-out reasons to run VMware Server on Linux are an easy-to-use command-line interface and the fact that the host OS is free (as in liberty, not beer).
So which operating system is the winner? The truth is that neither OS offers anything so dramatically superior than the other that either one is the clear winner. It boils down to your comfort level. If you are more comfortable running Windows, then host VMware Server on Windows, and the same goes for Linux. You will not be missing out on any amazing features either way, and you are bound to run the more secure installation on the host OS that you are familiar with.
*Editor's Note: This column inspired more than one response. Read the best one here.
Andrew Kutz is deeply embedded in the dark, dangerous world of virtualization. Andrew is an avid fan of .NET, open source, Terminal Services, coding and comics. He is a Microsoft Certified Solutions Developer (MCSD), a SANS/GIAC Certified Windows Security Administrator (GCWN) and a VMware Certified Professional (VCP) in VI3. Andrew graduated from the University of Texas at Austin with a BA in Ancient History and Classical Civilization and currently lives in Austin, Tex., with his wife Mandy and their two puppies, Lucy and CJ.