QuickSpecs

Figure 4. Ducted fan cross-section and ducted fan blade compared to traditional server fan

Active Cool fans are controlled by the c-Class Onboard Administrator. The Onboard Administrator

can ramp cooling capacity up or down based on system needs. Along with optimizing the airflow,

the control algorithm optimizes the acoustic levels and power consumption. As a result, the c7000

enclosure can accommodate full-featured servers that are 60 percent more dense than traditional rack-

mount servers, while the Active Cool fans consume only 50 percent of the power typically required

and use 30 percent less airflow.

HP PARSEC architecture

The c7000 enclosure uses PARSEC architecture—parallel, redundant, scalable, enclosure-based

cooling. In this context, parallel means that fresh, cool air flows over all the blades (in the front of the

enclosure) and all the interconnect modules (in the back of the enclosure). The enclosure is divided

into four cooling zones with fans in each. The Active Cool fans provide cooling for their own zone

and redundant cooling for the rest of the enclosure. To ensure scalability, HP designed both the fans

and the power supplies with enough capacity to meet the needs of compute, storage, and I/O

components well into the future.

Parallel

To optimize thermal design, HP developed a relatively airtight center air plenum, or air chamber. In

the c7000 enclosure, all device bays include a shutoff door that is normally closed to prevent air

leakage through that device bay. When a server blade is inserted, it seals into the center air plenum

docking collar, and the server shut-off door opens to allow airflow across that server blade. Similarly,

the fan seals into the center air plenum docking collar. Each fan bay includes louvers that

automatically open when a fan is installed. If a fan is not installed or is not functional, the pressure

distribution around the fan changes. This pressure change causes the louvers to close, ensuring that

cooling air is not diverted through the non-operating fan (Figure 5).