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Virtual appliances vs. Physical appliances

Simon Sharwood

In the late 1990s, appliance computing was big news, as companies like Network Appliance (which has since changed its name to NetApp), championing the idea of a sealed box computer that did one thing very well, leaving organisations to rely on servers for applications and appliances for specific tasks.

Appliances were also engineered to provide the computing power needed to meet certain applications’ specific requirements, giving them a performance advantage over servers.

The concept took off: NetApp made its name in the field, and many companies followed into the market with appliances for security and other tasks. Microsoft even created a cut of Windows Server, called “Windows Powered Specialized Servers,” to turn servers into appliances. Some OEMs even created white box appliances.

One reason for the appliance fad was the obvious success of networking products.

“We were blatantly emulating Cisco,” says John Martin, a Consulting Systems Engineer at NetApp. “It [Cisco] had the idea that instead of running routing on a generalist OS, why not have a specialist operating system. We (NetApp) started as a software company and our value proposition was about a dedicated service. Putting it into an appliance solved appliance solved quality issues.”

Novell Technical Specialist Craig Wiley also remembers the appliance wave fondly.

“Hardware appliances were designed to make deployment simpler by giving end users a turnkey solution,” he

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says. “They could just power up a new hardware appliance, make some minor configuration changes and start to realise business value of the solution without concerning themselves with hardware and OS installation and application installation.”

Appliances became a computing mainstay, but of late a new type of appliance is becoming prominent: the virtual appliances.

Enter virtual appliances

Virtual appliances, like their physical cousins, are designed to do one thing, and do it well. But instead of residing on specially- engineered, dedicated hardware, virtual appliances are designed to run somewhere in a collection of virtual servers.

WAN optimisation vendor Blue Coat recently released such an appliance, and the company’s senior director of product marketing Mark Urban says “VMware lets us run our proprietary operating system and still be portable,” adding that a virtual appliance “... also offer[s] an environment that’s highly conducive to high-availability and real-time operations.”

Michael Chanter, Head of Professional Services at Frontline Systems, agrees that the move to virtual appliances does not necessarily mean a lessening in performance.

“The hardware can be tuned to the specific workload requirements,” he says.

Bede Hackney, Application Networking Group manager at Citrix, feels another benefit virtual appliances deliver is simplicity for the IT department.

“Hardware appliances are often expensive outlays for IT departments,” he says. “As such, there is the pressure to maximise their use. With a virtualised appliance, there is not such a restrictive cost involved, meaning that customers are able to use a virtual appliance for an individual appliance if required, leading to an application-specific infrastructure. This improves application performance and security, and creates an easily manageable, dynamic IT infrastructure.”

These benefits mean virtual appliances are generating plenty of interest, and Novell’s Wiley says the company “is seeing incredible demand for its virtual appliance builder tools.”

Yet while virtual appliances allow IT departments to get the benefits of appliances, without the need to manage a fleet of diverse devices from different vendors, physical appliances are not dying out. Blue Coat’s Urban says buyers of virtual appliances have different needs to those who shop for their physical cousins.

“The segment that’s expected to buy something like this [Blue Coat's new  virtual appliance]   ... operates differently [from physical  appliance customers],” he says. “This is for people who are concerned about having a discrete piece of equipment to manage – who are trying to reduce the number of boxes in the rack.”

NetApp’s Martin also says that virtual appliances aren’t likely to replace physical machines.

“All the hardware stuff is just there to accelerate certain functions. In a virtual appliance you miss that ability to use hardware to accelerate certain software functions."

“'Big tin’ will always have a part to play.”