Giants have always seemed destined to fall. But while the demise of monolithic, general-purpose servers in enterprise computing is not yet imminent, a relatively new class of smaller server appliances has been creeping up and brandishing a slingshot. Thin servers?a.k.a. server appliances or ultradense servers?won\u2019t boldly go where larger, traditional servers cannot (unless you count exceptionally small closets). They do essentially the same things as their larger brethren. But instead of trying to be all things to all users, thin servers support a single activity simply, reliably and inexpensively. According to Pushan Rinnen, an analyst with Stamford, Conn.-based research company Dataquest, these features will help the server appliance market experience 62 percent compound annual growth rate from 1999 (slightly under $1 billion) to 2004 (more than $10.5 billion).Doing One Thing WellCommon server appliances provide a straightforward solution to a standard server function?printing, Web serving, e-mail, file sharing and such. They are usually bare-bones devices costing less than $2,000 and designed to fit in single-space, rack-mounted cases the size of your average pizza box. Installation generally involves plugging them in, turning them on and configuring a few settings through a simple browser-based interface. Once configured, they can be pretty much left alone to do their jobs with minimal intervention. And if one goes down, you simply pop another of the devices into its place. Appliances also have another appeal, says Giga Information Group analyst Stacey Quandt in Santa Clara, Calif. Companies can purchase the appliances as needed, and they cost relatively little compared with most traditional servers. As a result, enterprises can realize return on investment in months rather than years. That said, there are significant drawbacks to the thin server model. The de-vices are usually designed to do one thing and one thing only. If you suddenly need more firewall protection and less Web serving, you can\u2019t reconfigure your existing thin servers to perform the necessary tasks. And today\u2019s servers often use mobile processor technology and less expensive (nonerror correcting) RAM to reduce costs and keep power consumption low, but such components don\u2019t have long histories of reliability in the server space. Given those caveats, companies must be careful about where they incorporate the devices. Despite the question marks, many big-name computer vendors, such as Compaq, Dell and IBM, have begun jumping into the thin server market along with small makers, the likes of Los Gatos, Calif.-based FiberCycle Networks; Rebel.com in Ottawa, Canada; and RLX Technologies in The Woodlands, Texas. The power of the lure to thin servers is evident: Compaq even filed suit against startup RLX, alleging that the new company stole away key high-density server developers from Compaq projects. "Everybody\u2019s chasing that appliance server model," says Mark Bayliss, president and CEO of Winchester, Va. -based Visual Link Internet, an ISP and virtual hosting service. "They\u2019ve all contacted us and said they\u2019re coming out with something." Bayliss\u2019s company chose to work with Cobalt Networks in Mountain View, Calif., a company that Quandt calls the market leader in appliances. Many other analysts and insiders agree, pointing out that Cobalt almost single-handedly created the server appliance market as we know it, carving their own niche full of stylish bright-blue boxes some four years ago. (Sun Microsystems recently acquired the company in a move intended to bring Sun a solid measure of market penetration in both the areas of high- and low-end servers.) Applying the Appliances Visual Link had been building its own Linux machines for dedicated Web hosting until it noticed a considerable market potential in hosting sites on appliances instead. The company soon struck up a strategic agreement with Cobalt, creating CobaltRacks.com, and began to almost immediately sell more than 200 servers per month (customers "buy" a Cobalt system to host their site, but Visual Link maintains the hardware at their own site). "The appliance-hosting market allowed the people who had the marketing skills, without the problem of having an IT department, to go directly into [the website] business," says Bayliss. In addition, technical support costs?Visual Link\u2019s largest expense after buying bandwidth?fell by 90 percent, according to Bayliss, because the thin servers required less regular maintenance and fewer experienced administrators than the older Linux boxes. Derek Linders, a technical specialist with Mississauga, Canada-based EDS Innovations, a consulting and solutions provider, similarly had been eyeing server appliances, but he hit a snag when he tried to develop a low-cost solution for a customer that would cover firewall protection, Internet sharing (for 50 PCs on one DSL connection) and remote access to servers for e-mail, voice mail, and server maintenance and support. Then Linders found the box he was looking for from Rebel.com. The company manufactures the NetWinder 3100, a product that can act as a file server, virtual private network gateway, print server, Web server, e-mail server, collaboration server, Internet firewall and proxy. Linders discovered only after his search that the CEO of NetWinder and his own CEO are brothers.While tapping into the allure of appliance simplicity and a browser-based interface, the NetWinder has an additional edge: lower power consumption?a requirement for some and a pleasant bonus for others. In late February 2001, Rebel.com released the first server based on a Transmeta Crusoe chip, originally designed for laptops?a chip that consumes approximately one-fourth the power of a similar Intel processor. This is a significant issue for companies running rooms filled with servers. While not as touchy about temperature as old-world mainframes, traditional servers often still require cooling systems to deal with their heat and avert potential meltdowns. But low-power servers, such as the NetWinder, allow enterprises to safely cram more servers into a space, again helping to reduce costs. And other vendors are quickly following suit: FiberCycle Networks is using Transmeta pro-cessors for its WebBunker thin server, as will RLX Technologies when its products ship later this year. Staying Thin? Despite their advantages, thin servers need to expand their offerings beyond the simple chores they now perform if they intend to keep expanding their markets. But that should begin to happen soon. "We\u2019re going to see more ISVs [independent software vendors] targeting the appliance architecture, and developers looking to these applications and developing to the appliance," observes Quandt. Significant trends will open up the servers\u2019 architectures and application program interfaces, expanding options for CIOs looking into thin server technology. This could mean that IT departments will have their development teams writing software for thin servers and that software vendors, such as Microsoft and IBM, will write software for specific thin clients. Next-generation technologies could make these servers even more appealing, according to Crawford del Prete, senior vice president for hardware research at IDC (a sister company to CIO\u2019s publisher, CXO Media). Several server makers?including Intel spinoff Ziatech in San Luis Obispo, Calif., and San Jose, Calif.-based Force Computers?have already borrowed the "blade" form factor from routers (ultra-thin rack-mountable slices that contain complete systems) and can now stuff a half dozen or more processors into a space formerly taken up by two CPUs. And while today\u2019s thin servers are built with a single, immutable purpose in mind, del Prete says future versions will act as adaptive pools of computing resources, able to switch among a variety of tasks. Such systems, however, are a few years off, however. Today, even the devices\u2019 boosters raise a note of caution. For organizations that say they want to "do database and sales" and "run a couple hundred clients on each machine," thin servers are not only appropriate but also appealing, Bayliss says. But, "there are still jobs where thin servers will not compete," he says. If you want to host a Yahoo or an extremely large site, this isn\u2019t the place to look, he adds. Others concur. "I don\u2019t think any large enterprise is going to run their entire operation off a couple of appliance servers," observes Summit Strategies analyst Harve Tannenbaum. "As a piece in the mix, however, they can be a wonderful tool." Freelance Writer Matthew W. Beale is working on several fiction projects and creating a new magazine-website that will cast a critical gaze at technology. He can be contacted at email@example.com.