Appliance: n. [uh-plahy-uhns] an instrument or device designed for a particular purpose. 2. a piece of equipment, usually operated electrically, esp. for use in the home, as a refrigerator.
For years, I thought an appliance was a mechanical do-dad found in my kitchen, as in a toaster or an easy-bake oven.
But then I started working with IT and learned an appliance is a boxed solution dedicated to running a specific software. Usually, I learned, they plugged into your system and were for things like networking, security, caching, middleware and so on. Got it.
So perhaps I can be forgiven for doing a double take when I read about virtual appliances, a concept that seems to defy any of the accepted definitions for "appliance," as well as common sense.
A virtual appliance does just what a normal appliance does, but without the hardware. If it sounds suspiciously like software, that's because, at its core, it is. The key difference is that software operates on an OS and becomes a part of your system, whereas virtual appliances ship with a trimmed-down OS and other functions they will need to run all by themselves, minus the hardware.
Think of a virtual appliance as that weird uncle who comes to your family reunions. He married your aunt so, technically, he's family. But, since he keeps to himself and never quite fits in, he's really still an outsider.
So how do virtual appliances fit in with enterprise integration?
Not well, apparently. As Andi Mann of Enterprise Management Associates explains in this CIO Update column, the cons of virtual appliances outweigh the benefits.
True, virtual appliances are simple to install, cost-effective and relatively secure. But, they don't play well with other enterprise tools, including performance management and monitoring solutions, according to Mann. They're also tricky to support and, like other virtualization efforts, virtual appliances can create security problems.
To me, that sounds like a zero-sum game. Mann doesn't disagree, concluding that virtual appliances ultimately offer the worst of both software and appliances.