The XenServer Administrative Console
If the XenSource AC ever found itself on a particular game show, it would suffer the wrath and public humiliation of having the host point at it and utter the words, "You are the weakest link, goodbye!" It's hard to pin down exactly what it is about the AC that makes it seem so unpolished. Perhaps it's because the application is split horizontally instead of vertically, and this format does not lend itself well to an ever-expanding list of hosts and VMs that appears in the upper section. Perhaps it's because when the application is resized, the upper and lower sections are not resized relatively. Instead, the lower section fills the entire application window in an attempt to retain its original size, thereby completely hiding the upper section from view. Then again, it could be because the application is written in Java, a language that has never resulted in any GUI that feels at home next to an OS's (operating system's) native window decorations.
While some may not care that the AC has visual kinks that need to be worked out, this application is the first and last glimpse at Xen that many people will see.
While testing XenServer, the host server sat next to the computer running the AC the entire time -- an open laptop with the screen turned off because it was not being used. At one point a curious individual pointed to the desktop's monitor and said, "That's Xen?" It was explained that the desktop monitor displayed merely the interface to Xen, and that the laptop sitting to the right was actually running the virtualization software. The point of this anecdote is to illustrate that for most people, an interface to a technology is all they ever know -- hence to them, the interface becomes the face of the technology. While XenServer may be a tremendous hypervisor, if its interface is not cleaned up, some people may judge a book by its cover and put that book back on the shelf.
Other XenSource annoyances
It's not just the visual aspects of the AC that are problematic. The XenServer ISO image comes with a Windows installer and a Red Hat package for installing the AC, but there is no Debian package or at the very least a tarball with the AC's sources. The AC may only support Windows and Linux distributions with RPM support, but XenSource could have at least included the AC's sources so people who use Ubuntu, for example, could install the AC on their desktops without having to go find another computer.
Another feature that the AC lacks is administrative delegation. The only user that can log into a host server from the AC is the root user. Even if other users exist in domain-0 on the host server, the AC restricts host logins to the root user. This greatly limits the ability to widely deploy XenServer in a distributed environment since it may not be desirable to hand out root credentials to every administrator that needs to administer a VM with the AC.
The AC also lacks template support; it is not possible to create templates of Windows VMs and then deploy VMs from those templates when needed. Yes, the AC can clone a VM, but that is not the same thing. A template system would integrate the Microsoft System Preparation utility so that new VMs could be rolled out and transformed in one fell swoop.
While the performance indicators that the AC displays about the XenServer hosts and their VMs are nice, it would be even nicer if they were in more than just real-time. There is no option to view historical performance and this is a must-have feature for shops that have to build road maps. To get where you are going, you have to know where you have been. It would also be nice to export usage data to some kind of file format -- OpenOffice Calc, Microsoft Excel, or even a plain-text delimited value file.
Even tomes in dire need of a rewrite may still possess redeeming qualities. One of the nicest features of the AC is the immediate, detailed overview it gives you of all of the XenServer hosts and their VMs. The list of hosts and VMs in the upper section all have their CPU usage, memory usage, and disk and network activity displayed in easy-to-read formats.
XenSource also provides a feature with the AC that is sorely lacking in many of today's more "enterprise" applications. The AC has a wonderful online help support system. Most GUI applications have some sort of help library that seems to be the result of some developers attempting to prove the "12 monkeys in a room with a pencil will write Shakespeare" theory, when in actuality all that ends up happening is some foul smelling material is flung onto a few pages. This is not the case with the AC; its help system is simply terrific.
Another nice touch: You don't need a separate application to gain console access to the XenServer hosts. While there will always be a reason to have a terminal (or terminals) dedicated to the XenServer host, it's nice to be able to connect to them within the AC by just selecting a host, clicking on the "Text Console" tab, and logging in as the root user. This feature is particularly useful when using the AC on a Windows client since Windows does not ship with an SSH client.
One of the nicest utilities provided by the XenServer AC is not actually a part of the AC. When the AC is installed, a command-line utility named "xe.exe" gets placed in the directory called "bin" in the AC's installation path. This nifty little application makes it possible to script almost any task that can be accomplished with the XenServer AC, from installing a new VM to adding a virtual hard disk to a VM that already exists. In essence, "xe.exe" is the little application that could, and no XenServer administrator should leave home without it! For a full description of what "xe.exe" can do, the online help system that comes with the AC, "xe.exe" is listed under the topic "Command line interfaces."
All-in-all, the AC does about as many things right as it does wrong. While that is certainly a ratio that is miles ahead of many other applications released these days, it is not enough to make it stand out in the marketplace of virtualization management software. We are entering an age (some would say we have already arrived) in which all leading hypervisors will approach or reach bare-metal performance. The barometer used to measure a virtualization solution's worth does not take into account the VM monitor, but instead considers the management tools. However, none of that even matters. XenSource knows what features it must add, what capabilities its competitor's products have that its products lack and XenSource will get there. For a company whose founders created an entirely different way of looking at virtualization, what may be the most interesting point of all is what new features XenSource has planned for their management suite that no one has even thought of yet.
While there are flaws in XenServer, overall it's a solid product. Even more promising, XenSource is aware of many of the flaws and is actively working to correct such things as missing template support, lack of historical performance data, no ability to delegate, and a rewrite of the management console. XenSource is also working on added support for back-end storage plug-ins and increased 64-bit support.
XenServer is uniquely positioned to capture a yet untapped market -- mid-tier, bare-metal, Windows virtualization. Windows systems administrators will delight in being able to virtualize their OS without having to worry about patching an underlying OS or having to download an SSH client to manage the host server. Time will tell the whole story of XenServer, but the first chapter is shaping up to be a very interesting read indeed.
FN#1: In order to avoid confusion, from this point forward in this article, the use of XenServer will reference the specific product, and not the XenServer product family unless otherwise stated.
About the author: Andrew Kutz 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, Texas with his wife Mandy and their two puppies, Lucy and CJ.