NonStop NS2400 Series Planning Guide

Cooling and Humidity Control
Do not rely on an intuitive approach to design cooling or to simply achieve an energy balance—that
is, summing up to the total power dissipation from all the hardware and sizing a comparable air
conditioning capacity. Today’s high-performance servers use semiconductors that integrate multiple
functions on a single chip with very high power densities. These chips, plus high-power-density
mass storage and power supplies, are mounted in ultra-thin server and storage enclosures, and
then deployed into computer racks in large numbers. This higher concentration of devices results
in localized heat, which increases the potential for hot spots that can damage the equipment.
Additionally, variables in the installation site layout can adversely affect air flows and create hot
spots by allowing hot and cool air streams to mix. Studies have shown that above 70°F (20°C),
every increase of 18°F (10°C) reduces long-term electronics reliability by 50%.
Cooling airflow through each enclosure in the NonStop NS2400 series system is front-to-back.
Because of high heat densities and hot spots, an accurate assessment of air flow around and
through the server equipment and specialized cooling design is essential for reliable server
operation. For an airflow assessment, consult with your HP cooling consultant or your heating,
ventilation, and air conditioning (HVAC) engineer.
NOTE: Failure of site cooling with the server continuing to run can cause rapid heat buildup and
excessive temperatures within the hardware. Excessive internal temperatures can result in full or
partial system shutdown. Ensure that the site’s cooling system remains fully operational when the
server is running.
Because each modular cabinet houses a unique combination of enclosures, use the “Heat Dissipation
Specifications and Worksheet” (page 80) to calculate the total heat dissipation for the hardware
installed in each cabinet. For air temperature levels at the site, see “Operating Temperature,
Humidity, and Altitude” (page 81).
Weight
Because modular cabinets for NonStop NS2400 series systems house a unique combination of
enclosures, total weight must be calculated based on what is in the specific cabinet, as described
in “Modular Cabinet and Enclosure Weights With Worksheet” (page 78).
Flooring
NonStop NS2400 series systems can be installed either on the site’s floor with the cables entering
from above the equipment or on raised flooring with power and I/O cables entering from
underneath. Because cooling airflow through each enclosure in the modular cabinets is front-to-back,
raised flooring is not required for system cooling.
The site floor structure and any raised flooring (if used) must be able to support the total weight of
the installed computer system as well as the weight of the individual modular cabinets and their
enclosures as they are moved into position. To determine the total weight of each modular cabinet
with its installed enclosures, see “Modular Cabinet and Enclosure Weights With Worksheet”
(page 78).
For your site’s floor system, consult with your HP site preparation specialist or an appropriate floor
system engineer. If raised flooring is to be used, the design of the NonStop NS2400 series system
modular cabinet is optimized for placement on 24-inch floor panels.
Dust and Pollution Control
NonStop NS2400 series systems do not have air filters. Any computer equipment can be adversely
affected by dust and microscopic particles in the site environment. Airborne dust can blanket
electronic components on printed circuit boards, inhibiting cooling airflow and causing premature
failure from excess heat, humidity, or both. Metallically conductive particles can short circuit
Cooling and Humidity Control 49