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7 half-truths about virtualization
- — 28 July, 2009 06:57
3. Virtualization automatically reduces power use
If you have consolidated onto fewer servers, it might be tempting to say "I've solved my power use problems." Not so fast. While you now have fewer servers using up watts, each server is running at a higher CPU capacity and has greater power needs. At Brandeis University in Massachusetts, a virtualization project has actually increased overall power use, reports network and systems director John Turner. Although Brandeis dramatically reduced its number of servers, it is now offering more services to users because spinning up new VMs is so easy. Each new workload increases power use.
"If you walk behind the racks of virtualized servers, the heat is just pouring out of those guys," Turner says. "We're seeing heat dump into these rooms like never before."
Another issue to consider: If you're shutting off lots of servers, a data center has to be reconfigured to prevent cooling from being directed to empty space, explains APC CTO Jim Simonelli.
"The need to consider power and cooling alongside virtualization is becoming more and more important," he says. "If you just virtualize, but don't alter your infrastructure, you tend to be less efficient than you could be."
4. Virtualization makes me safer
The ability to clone VMs and move them from one physical box to another opens up great possibilities for disaster recovery -- and that in turn protects your business from data loss and downtime. But virtualization, if not managed properly, also brings new security risks that could threaten the safety of data and continuity of business systems.
People and processes are often not ready for virtualization and the security risks it introduces, IBM security expert Joshua Corman has argued.
Virtualization brings new attack surfaces and various operational and availability risks. Consolidating many applications onto a single server "gives you a single point of failure," DiDio notes.
If you're suffering from virtual server sprawl, it may be difficult to keep track of all your VMs, and it may thus be difficult to ensure that all of them are properly patched. Also, hypervisors do not perform encryption, leaving open the possibility of man-in-the-middle attacks such as Xensploit, which intercepts unencrypted data when VMs are migrated between physical servers.That doesn't mean you should avoid virtualization altogether, but it's often best to start with minor systems and work your way up to mission-critical applications.
5. Desktop virtualization will save me money right away
Virtualization should make it easier to deploy new desktops to users, apply patches and perform other management tasks. Desktop virtualization can also save money in the long run. A Denver transportation agency is expecting a $619,000 ROI over eight years by purchasing thin clients that will last longer than traditional PCs.
But IT shops have to remember desktop virtualization requires significant upfront costs, from purchasing user devices such as thin clients to back-end infrastructure such as servers, PC blades and networked storage to support VMs.
Anecdotally, Forrester Research analysts have found that enterprises spend about $860 per user, plus network upgrades, to get a desktop virtualization project up and running in the first year. A well-done desktop virtualization can certainly cut long-term costs. It just might take a few years to achieve ROI.
6. Virtualization is the same as cloud computing
Virtualization is a key enabler of cloud computing. But installing VMware on a few servers doesn't mean you've built a private cloud. In addition to virtualization, a private cloud requires service automation technologies and a self-service interface for provisioning new resources, says IBM cloud software chief Kristof Kloeckner.
In a blog post titled "virtualization isn't cloud computing," cloud start-up Enomaly's founder Reuven Cohen says virtualization is a building block for cloud computing, but the real key is abstraction at every level of the IT stack.
"The key to cloud infrastructure is abstraction to the point that it 'just doesn't matter,'" Cohen wrote. "Your infrastructure is always available and completely fault tolerant. Think more along the lines of the iPhone application delivery model (App Store), and less like the desktop application models of the past. The companies that will succeed are the ones who embrace this new hybrid internet centric model. More simply, the cloud is the computer."
A cloud doesn't necessarily even need virtualization. This has been proven by none other than Google officials, who have said they do not virtualize production hardware and instead use a job scheduling system of Google's own design to manage its many thousands of servers.
7. Virtualization is all about technology
This one won't surprise any longtime IT veteran: Sometimes, it's the people and not the technology that gets in the way. As Corman noted, people and processes are often not ready for the new challenges raised by virtualization.
Even if your virtualization project is a hit, you might become a victim of your own success. Once users might realize how easy it is to spin up a VM, they may become more demanding, making it harder for IT to focus on other tasks. Conversely, there may be resistance from users who prefer to stick with physical servers.
Pradel likes to call politics the "eighth layer" of the network stack.
"The political layer is the most difficult thing you have to deal with as far as virtualization goes," Pradel says. "You have members of your business community who I like to call serer huggers. They do not want to get rid of their physical machines, even though they will benefit from going to virtual."