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Blades: Good fit, bad heat, but nothing ugly

Are blades servers the best choice for virtualization? Or are their reputed benefits really not all they're cracked up to be? This article examines these much-hyped servers in terms of their physical space requirements, form and cost.

Blade servers are a force to be reckoned with in the hardware sector right now because of their potential benefits, such as convenience and reduced IT expenses. As more and more companies begin to jump on the virtualization bandwagon, they have to decide whether blades are a good choice for hosting these applications.

In some cases, blades are top notch, but in other cases, the hype is greater than the actual benefits that these servers deliver. This article examines each of blades' reputed benefits: reduced physical space requirements, lower cabling requirements and total cost of operation.


One main selling point of blades is that they can shrink traditional servers into small form factors, allowing them to be housed in a central chassis. Theoretically, a dozen blade servers would be simpler to deploy, easier to manage and less expensive to run than a dozen tower, rack or mainframe servers.

Ease of deployment was what convinced IT managers at John C. Lincoln Hospitals, which operates 440 beds and has 4,000 employees, to deploy blades in support of its ClearCube Technology Inc. virtualization software.

"We have a fast moving IT environment that changes from moment to moment, and we require IT solutions that can keep pace," said Rob Israel, CIO at the hospital. Because they are compact and designed to be plug-and-play, blades can be deployed within a few hours, whereas other servers could take a day or two to configure.


Blades are a good fit when office space is expensive. "If a company has a severely constrained data center, then blades are a logical option," said Gordon Haff, principal IT advisor at market research firm Illuminata Inc. In these cases, the devices cut down on the physical space needed to house servers as well as the amount of cabling needed to connect the servers to storage systems and enterprise networks.

For these reasons, blade servers made sense to IT staff at Cellcom, the largest cellular company in Israel. The company -- which has about 3,000 employees, four data centers and close to 1,200 servers -- has stringent and fluctuating computing requirements.

"Our QA (quality assurance) and development departments were constantly asking for new servers that were mostly needed on a temporary basis, so they could be used as a sandbox," said David Barak, systems expert at Cellcom.

The employees' requests for new servers often arose at the last minute, i.e. "I need this ready by tomorrow morning," so the cellular carriers installed VMware's virtualization software to quickly provision new servers. Initially, Cellcom relied on rack servers but moved to blades to reduce cabling requirements and save on floor space.

Overall cost

Many people believe blades offer more than simpler deployment and a better form factor; current sentiment is that these systems cost less than alternatives. But this might be a misconception.

"The notion that 'smaller is cheaper' is not often the case with computer hardware," noted Jane Wright, a research director at Gartner Inc. "If you look at laptop computers, they usually cost more than desktop systems."

Blades have an attractive initial sales price, but the cost usually does not include the chassis in which the systems are housed. Consequently, blades can be an expensive option in some cases.

"If a company only fills up about half of the slots in its chassis, then the blades will cost more than traditional servers," said Patrick Lin, director of product management for data center platform products at VMware.

Blades carry similar financial considerations when it comes to heating and power requirements. Although the hardware promises economies of scale by consolidating functions like heating, it may not always deliver on such promises. As vendors consolidate servers into smaller form factors, heating requirements increase.

"There were some problems with first generation of blades running so hot that they could not function," stated Gartner's Wright. "Recently, vendors seem to have overcome these issues."

Sometimes, the solution meant developing more complex cooling systems. Although cooling is an obvious necessary, the new cooling system may require more power than other servers' cooling techniques. Consequently, another ripple effect from deploying blades may be that companies need to rewire the data center. This very situation arose at John C. Lincoln Hospitals.

"As we started to roll out our blade servers, we had to double the power available in our data center," noted Israel.

Another dilemma is that the blades can be less functional than other options. Blade servers usually do not have as many memory slots as rack servers, and that difference can be a significant drawback in virtualization applications, according to Cellcom's Barak.

The future of blades

Despite the precarious balancing acts, blade sales and revenue have been growing at faster rates than other hardware options, a trend that is expected to continue for the next year or two. Gartner's Wright said the initial hype surrounding blades is starting to die down; companies are beginning to understand the servers' strengths and weaknesses, and more firms are deploying them.

"Blades are not a panacea but they are good fit for certain applications," she concluded.

About the author: Paul Korzeniowski is a freelance writer in Sudbury, Mass. who specializes in technology issues.

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