What Exactly Is A Blade Server?

By SmallBusinessComputing Staff | Posted August 12, 2002
By Dan Orzech

The name of the game in data centers today is density. With server proliferation a constant problem, information technology departments are always on the hunt for ways to pack more computing power into a smaller space.

They may have found it, with the latest approach to servers, now beginning to emerge from computer vendors: blade servers.

The standard six-foot high server racks that fill computer rooms today can hold up to 42 1U servers, each 1-3/4" tall. But those racks also have 42 power supplies, 42 fans and 42 network cards and cables. By sharing these components among servers, and removing the sheet metal chassis that surrounds each server, blade servers squeeze many more computers in the same amount of space. The result is a sort of server farm in a rack. Blade server vendor RLX Technologies, of The Woodlands, Tex., for example, packs up to 336 servers in a standard 42U rack.

The blade approach emerged in the mid-1990s in the telecommunications industry, where switching equipment was mounted in racks using a blade-type standard called Compact PCI.

Blade servers are only just beginning to appear in enterprise data centers, however. RLX was founded in December 1999; another leading vendor, Egenera Inc., of Marlboro, Mass., opened its doors three months later. Both of those firms are currently shipping blade-based systems, as is HP. Sun, IBM and Dell all have announced plans to introduce blade servers later this year.

So far blade servers seem to be largely popular among ISPs and ASPs, and for applications such as email, Web and domain name serving. As they gain acceptance, and as vendors release more powerful systems, they are likely to start seeing duty for more mission-critical applications. Already, Egenera's BladeFrame system, which is targeted at high-end data centers, is finding its way into computer rooms on Wall Street. Brokerage house Credit Suisse First Boston earlier this year replaced 20 traditional RISC-based servers with a BladeFrame, which it uses to process more than 60 million financial transactions a day.

Cable Misery
Blade servers pack more processing power into a small space. They offer another advantage as well, one that at first glance might not seem tremendously significant: far fewer cables.

"Cable management is the bane of many a data center manager's life," says Jonathan Eunice, principle analyst at Illuminata. Look at the front of a rack of thin servers, he says, and you see a sleek, elegant computing design. Viewed from the back, however, the rack is a tangled mess of power, network, disk storage, keyboard and video cables.

In a large data center, says Eunice, dealing with the tangle can rapidly get expensive. Today, he says, "you can no longer afford to have your highly paid IT staff pulling cables all day, or drawing beautiful maps of what cables go where."

Because blade servers have internal, high-speed communication channels between the individual blades, they can dispense with network cards and cables for each server, and shared power supplies cut the number of electrical cords. The result is far fewer cables: Egenera's BladeFrame, for example, consolidates the cables for up to 24 four-way servers into as few as four cables.

That greatly simplifies administration. "In a traditional rack," says Sally Stevens, a product manager for blade servers at HP, "if you want to swap out a server, you have to go to the back, uncable it, take it out, migrate cards and recable it. With the blade, you pull out the old one and snap in a new one. It's as easy as changing a light bulb."

HP has simplified the process even further, says Stevens, with the addition of a simple blue light on the front of each blade. When a blade is shut down to be replaced, the light comes on, allowing it to be located quickly. That's a useful feature when a single rack can hold up to 280 blades, as HP's do.

Automatic Reprovisioning
While blade servers' simple physical architecture is appealing, the real payoff comes when that is combined with systems management software specifically designed for them. HP, Egenera and RLX all offer software packages to manage blade servers. The software keeps track of how each particular blade is configured. Replace a blade, "and the system automatically reprovisions it with the correct operating system and applications," says Stevens.

Managing the blades through software means companies can react quickly to changes in the business environment, says Bob Van Steenberg, RLX's chief technology officer. "As your computing needs change," he says, "you can reprovision the blades, entirely through software, to meet those changing requirements."

It also can dramatically reduce the cost of administering a data center. "RLX has several customers who've compared the cost of running traditional computers with the cost of delivering the same computing capability with blade computers," says Van Steenberg. "What they've typically seen is a thirty percent reduction in the cost of operation."

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