Scientists conducting experiments on addiction have shown that when mice are allowed to self-administer narcotics, such as cocaine, by pressing a lever, they will very quickly develop addictive behavior patterns - pressing that lever repeatedly, even until death by overdose. At a recent technology conference, an IT director described a very similar behavior that immediately reminded me of the addiction studies. In this case, however, the drug of choice was a virtual machine.

A virtual machine could be “spawned” with a few clicks, and, in a matter of minutes (instead of days, as with physical servers) lead to rapid sprawl of virtual machines. This comparison is only fanciful and not meant to downplay addiction, but the challenge of sprawling virtual machines is real. As companies consolidate servers to save on hardware, many are seeing an explosion in the deployment of virtual machines - often for trivial uses - replacing server sprawl with virtual server sprawl.

Unfortunately, virtual server sprawl is not as harmless as it might sound. Each virtual machine requires its own operating system license and additional licenses for any applications installed within. As a result, with the falling cost of hardware and the high cost of operating system licenses and application software you might be eating away those hardware savings! Other problems caused by virtual server sprawl include:

* Management overhead: Each new operating system and application image needs to be updated, monitored and managed.

* Security concerns: With patch management already a big headache for IT engineers, sprawling operating system images only make things worse. And if they are left unpatched or have an undiscovered bug, each one of these virtual servers can act as a springboard for an attack or be compromised and added to a “zombie army.”

* Wasted electricity: More virtual servers mean hotter CPUs and bigger electricity bills.

IT directors should attempt to control the growth of virtual servers as they would any other IT resource. Just because it is easy to spawn a new server doesn’t mean that it should be done without consideration for the bigger picture (management and security, see above). Many applications can co-exist within the same operating system installation or even application framework without problems - it is not necessary to spawn a new server.