Guest View: Lowdown on virtualization hype

By Don MacVittie

October 1, 2008 —

Picture a circle of children holding hands on a grassy hill. One wavering voice starts to sing, and soon the entire circle joins in, filling the air with the strains of “Kumbaya.”

That’s the feeling you get when someone says “virtualization” in a crowd of IT folks. Vacuous smiles break out as the conversation turns from serious talk about business requirements to platitudes about virtualization’s benefits. Rarely does anyone mention the issues virtualization creates or the processes required to keep things straight in a highly virtualized environment.

Virtualization is a great tool, but the industry buzz makes it sound as if virtualization is the entire toolbox. Frankly, if all you have is a hammer, everything looks like a nail—and these days all the nails seem to sport “Virtualize me” signs. Many of them should not be virtualized. But that doesn’t matter any more than it mattered in the heady days of XML that not every bit of data is best expressed as text.

Is virtualization good for eliminating hardware dependencies? Yes, in many cases. Running a VM of an operating system that you don’t otherwise support is a handy way to make old software run on new hardware. Is it a good way to merge all of those not-too-busy servers you installed in the days when Larry Ellison was admonishing you not to fall for the “lots of little boxes” solutions? Yes. Having 20 machines sitting around at 10% utilization is wasteful at best.

Is virtualization the right tool for every job? Was the wheel?

There are so many problems that virtualization cannot solve (or should not be used to solve) that we need to let the hype cycle run its course and get on with the business of IT.

If your solution needs to be load balanced, for example, virtualization is the worst solution at hand, unless you’ve got a process in place to guarantee that no two load-balanced instances will end up on the same box (since having two load-balanced instances on the same virtual server just creates more overhead, in the form of context switches and resource allocation/contention). Even then, if your application is so busy that it requires load balancing, why are you putting it onto virtualized servers with other applications?

Then there’s the “all of your eggs in one basket” scenario. Employees at one consulting firm have told me their entire infrastructure is a single virtualized server that pretends to be all things to all employees. That’s got “fail” written all over it. A single point of failure becomes a massive corporate meltdown pretty quickly. Granted, the firm is just starting up; still, hardware is cheap enough that the firm should have at least a couple of servers, so it can get things back up and running quickly in the event of a system catastrophe. But the buzz says they don’t need the hardware—they’re virtualized!

And server virtualization is the most useful of the virtualization technologies.

Let us not forget that for a very long time, storage area network vendors have been trying to sell customers what amounts to LUN (logical unit) virtualization, and for the most part customers have said, “No, thanks.” Funny thing: When you have block-based storage and a vendor says, “You don’t have to worry about where a given block is stored, because our box takes care of it for you,” customers still want to know where to find their data should the box go down. The answer usually is, “You can’t know; our box hides that from you!” End of SAN virtualization.

Some vendors look to alleviate customer concerns about SAN virtualization by offering services or tools to let them get the data off the virtual server if the device goes bad. But then customers ask, “What if I want to remove your device?” Traditionally the answer has been an implied, “You’re on your own.” Once again, end of SAN virtualization.

Network-attached storage virtualization in the form of unified directories is somewhat better; at least you can get at the data without going through the virtualization device. Some of the older products still rename things on the way through, but the industry learned long ago that renaming creates headaches.

Still, the case for putting “all 40TB of your corporate data in one directory tree” is weak. It does enable portability in some cases, but it’s no panacea. When a vendor tells me its products ease administration, I respond, “I used to have one directory structure for this data; now I have two. This is easier… how?”

Heterogeneous solutions require more hardware, and this is where file-level virtualization loses the race to server virtualization. The benefit of server virtualization is obvious; promise to merge three physical servers into one, and the densest IT admin will scurry to pay you. Not so for file virtualization, where the sales line is, “Put in this box, and the world will be a prettier place!” It’s a much harder sell to convince people that a unified directory structure will save them money when they’ll have more hardware to maintain, though in certain environments a unified directory justifies the cost of the virtualization devices.

As for desktop virtualization, politics is the only other arena in which someone can draw cheers by saying, “It’ll be less efficient, it’ll cost you more, it’ll be less adaptable, but it’s the right thing to do!” You’ll be spending the same amount on laptops and desktops (they have to run the same applications, after all); your network will see a ton more traffic while entire images are transferred; and your servers will store virtual desktop images, increasing their hardware requirements. Since a laptop solves “Get access anywhere and have the same desktop” requirements, why, exactly, do we need desktop virtualization?

Not that I begrudge the virtualization vendors their successes; there’s some great stuff out there. But I shake my head when our industry gleefully overreacts to new technologies that promise the stars, and sets budgets based upon what’s hot instead of what’s needed.

Don MacVittie is a strategic architect for F5 Networks’ DevCentral developer network.

Related Search Term(s): databases, desktop management, server management, virtualization

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