Before You Virtualize Servers: A Checklist
In the Fall of 2007, the IT department at Campbell Clinic Orthopaedics faced a problem: several servers were due or overdue for replacement, so the clinic would have to purchase up to 10 new ones during the coming year. “We could have gone the traditional route and bought 10 servers,” says Justin Lauer, director of IT. Instead, the clinic bought three physical servers and installed virtualization software on both new and existing machines.
Today, Campbell Clinic has 20 to 25 virtual servers running at any given time. The number varies because Lauer and his team create extra virtual servers as testing environments for new software, and then delete them when they’re through. Virtualization has worked out great, he says. “We did it because of an aging infrastructure, but we all got the benefits of consolidation and the flexibility to create new servers at will. And we didn’t realize until we did it how good it would be for our disaster recovery plan.” Since a virtual server is stored as a single file, it’s easy to reload that file on new hardware and get it up and running in case of need, he explains.
But while virtualization brings major benefits, it also comes with a few challenges that should be addressed right from the start. Before you virtualize, make sure you have answered the following questions:
1. Will our servers need more RAM? The answer is almost certainly yes. “RAM is the key. I can’t stress that enough,” Lauer says. “RAM is the most used resource in a virtual environment, so don’t expect to get a server and throw a couple of gigabytes of RAM in it. You’re going to max out the RAM. It’s common for servers hosting virtualization to have 32 gigabytes.”
2. What about other resources? For x86-level servers (the low-end, desktop-computer-like servers most small companies use), virtualization can strain more than just RAM. “You have to plan for all the different hardware requirements,” Lauer says. In addition to RAM, these could include more processing power, network input/output (I/O) capacity, and bandwidth. “If you’re trying to run 10 virtual servers on a physical server with only two network cards, that will create a bottleneck,” he says.
3. Are we prepared to cool “hotspots”? One of the best arguments for virtualization is reduced power consumption: fewer physical servers will draw less power, and also require less cooling. While all this is true, your newly virtualized servers will be working much harder than your servers did before, and this can create isolated “hotspots” where temperatures can rise rapidly.
“The amount of heat you need to dissipate can increase by factors of 10, especially if you’re putting in blade servers or high availability hardware,” says Bob Waldie, CEO of Opengear, which provides infrastructure management. “You were using hundreds of watts, and now you’re using kilowatts on that one device.”
4. How will we deal with hardware failures? “When you had a larger number of servers running one or two applications each, a hardware failure would only have removed a little piece of your functionality,” Waldie says. “When you have eight or 10 servers running on one physical device, you could lose a lot more mission-critical function if the hardware goes down.” This is why many smart companies put in high availability solutions, with failovers in place in case a server does down, at the same time that they virtualize.
5. Can IT staff deal with increased complexity? “If you had 25 servers before, and now you have far fewer, it may seem like you’ve reduced the complexity,” Waldie says. “In fact, you’ve increased it. You still have exactly the same number of servers running, only some of them are now virtual. In addition, you have the virtualization software itself to manage.”
How will your team cope? Training is the best strategy, according to James Staten, principal analyst, Forrester Research. “Make sure whoever will be responsible for the virtualization software is certified on that product,” he says. “If not, you should send them for certification.”
6. Are we ready for the future? Waldie advises reviewing the physical environment and architecture you’re currently planning to use for virtualization, with a view to the next three years. Will your racks and other equipment be able to handle the densities, workload and cooling needs you’re likely to encounter, especially if your company is growing?
“Even though adoption of virtualization is ramping, the tools don’t generally work across platforms,” he says. Yet mergers or other developments may force you to work with different brands of virtualization software. “You should get some expert advice about how to architect your virtualized system to gain flexibility,” he says. “It seems simple, but it’s not.”
In time, it will probably get easier to work with two or more brands of virtualization, and “platform-agnostic” tools will be developed, he says. “The thing about virtualization is, it’s still very early days.”
SIDEBAR: Want to Try Out Virtualization Software?
To truly reap the benefits of virtualization, you’ll want to install a hypervisor that replaces the operating system as the “bottom-of-the-stack” on your server, and runs everything in a virtual environment. If you need to quickly add a virtual server to an existing setup, or just want to give virtualization a try to see how it works, other software options will allow you to add one or more virtual servers to an existing setup.
Many providers offer low-end versions of both types of software as a free download. Here are just a few: