In-Depth

Blade Server Demand Driving High-Density Zones

High-density zones strike a balance between the power and cooling requirements of different kinds of data center assets. The rub, of course, is that they'll cost you.

• By Stephen Swoyer
• 03/22/2011

Blade servers are flying on to data center shelves at a breakneck pace. There's so much demand for blades, in fact, that market watcher Gartner Inc. projects that data centers will implement so-called "high-density zones" (HDZs) just to accommodate their blade assets. "High-density zones are by far the best way to manage the differences in the life cycle changes of data centers' building structures, electromechanical equipment, and IT equipment," said Rakesh Kumar, research vice president at Gartner, in a statement.

In just four years, Kumar and Gartner project, half of all data centers will incorporate HDZs.

One issue, according to Kumar, is that many potential customers still don't understand the what and the wherefore of HDZs, which -- like any technology proposition -- have both benefits and drawbacks: "Many users remain unsure of the benefits of high-density zones -- especially in gaining flexibility in capacity planning -- as well as the potential pitfalls."

So what is an HDZ? According to Kumar and Gartner, it's a region in data center space where energy requirements exceed more than 10 kilowatts (kW) per rack "for a given set of rows."

If your data center is more than half a decade old, you'll likely have to think about giving it an HDZ retrofit. After all, Gartner notes, most "legacy" data centers are designed to accommodate a "uniform" energy distribution of between 2kW and 4kW per rack.

Practically speaking, Gartner observes, "any standard rack of blade servers that is more than 50 percent full will need to be in a high-density zone."

HDZs provide a good way to strike a balance between the power and cooling requirements of different kinds of data center assets, including servers, storage devices, and networking gear.

The cost and complexity of an HDZ is a function of its density: the denser an HDZ, the greater the cost to design, build, and (of course) operate it.

In most cases, forced-air cooling -- a mainstay of data center design for decades now -- won't be enough. "Traditional forced-air cooling methods become increasingly ineffective at densities above 15kW per rack," the Gartner release said. "A high-density zone will, therefore, typically require supplementary cooling, such as a chilled-water system, hot/cold aisle containment or in-row/in-rack cooling."

The takeaway, says Kumar, is that shops must now expect to manage the lifecycles of their electromechanical infrastructure assets, in addition to those of their IT systems.

"One of the most-important strategic considerations in designing new data centers or refurbishing existing ones is balancing the rates of change between the building's system and the IT systems," said Kumar. "For example, over a 15-year period, a building will remain essentially the same, but the electromechanical systems will typically need one round of modifications, while the IT systems will typically be refreshed two to three times."