Why keep a server cabinet cool?

Networking equipment - especially servers - generates a lot of heat in a relatively small area. Today's servers are smaller and have faster CPUs than ever. Because most of the power used by these devices is dissipated into the air as heat, they can really strain the cooling capacity of a data centre. The components housed in a medium-sized data centre can easily generate enough heat to heat a house in the dead of winter! If servers and other networking equipment are not kept cool, they're prone to failure and a shortened lifespan. Damage caused by heat is not always immediately evident as a catastrophic meltdown - signs of heat damage include node crashes and hardware failures that can happen over a period of weeks or even months, leading to chronic downtime.

Computer rooms generally have special equipment such as high-capacity air conditioning and raised-floor cooling systems to meet their high cooling requirements. However, it's also important to ensure that individual cabinets used for network equipment provide adequate ventilation. Even if the data centre is cool, the inside of a cabinet may overheat if air distribution is inadequate.

How to keep a server cabinet cool

The temperature inside a cabinet is affected by many variables, including door perforations, cabinet size, and the types of components housed within the cabinet. The most direct way to cool network equipment is to ensure adequate airflow. The goal is that every server, every router, every switch has the necessary amount of air no matter how high or low it is in the cabinet. It takes a certain volume of air to cool a device to within its ideal temperature range. Equipment manufacturers provide very little guidance about how to do this; however, there are some very basic methods you can use to maximise the ventilation within your cabinets.

1 - Ensure airflow through cabinet door

Most major server manufacturers recommend that the front and back cabinet doors have at least 63% open area for airflow. You can achieve this by either removing cabinet doors altogether or by buying cabinets that have perforated doors. Because most servers, as well as other network devices, are equipped with internal fans, open or perforated doors may be the only ventilation you need as long as your data centre has enough air-conditioning to dissipate the heat load. You may also want to choose cabinets with side panels to keep the air within each cabinet from mixing with hot air from an adjacent cabinet.

2 - Determine type of convection cooling needed

a) Natural convection cooling

The flow of heat from a warmer environment to a cooler environment occurs naturally when the ambient temperature surrounding an IT cabinet is cooler than the internal temperature. The heat from the enclosure will naturally radiate through its walls, and the internal temperature will be lowered accordingly. Although this method is by far the simplest, it is also the least effective because the temperature difference between most enclosures and their ambient environments is not big enough to sufficiently cool the components inside the enclosure.

b) Forced convection cooling

The amount of heat that transfers from a warmer area to a cooler area can be increased with the addition of a fan or blower to decrease the thermal resistance of the barrier between the two areas. In the case of an IT enclosure, fans can provide affordable forced convection cooling to reduce the internal temperature. But what happens when the outside air has contaminants like dust and dirt or oil? The fan may provide the cooling you need, but it will deposit these contaminants on electrical components at the same time. When air contamination might be a problem, the best solution is a closed loop air-to-air heat exchanger. However, just as with natural convection cooling, the amount of heat that can be transferred away from the components inside the enclosure is limited by the ambient air temperature.

c) Active convection cooling

When natural convection or forced convection does not provide enough heat transfer to adequately cool the components inside the enclosure, an air conditioner may be required. An air conditioner provides the closed loop system that is needed when the components inside the enclosure must be protected from environmental factors such as dirt, dust, or liquids. Furthermore, air-conditioned cabinets - like Black Box's ClimateCab™ Climate-Controlled Cabinets - even let you save energy, because you only need to cool the cabinet and not the entire room or IT center.

Calculating the required cooling capacity is an essential step in selecting a properly sized air conditioner. Cooling capacities for enclosure air conditioners range from 1.000 BTU/hour to 20.000 BTU/hour, which is based on the internal heat load and the heat load transfer. An accurate calculation is therefore a critical step in selecting the right AC unit for your application.

Get to know more about Black Box's ClimateCab™ Cooling Capacity.

3 - Placement of equipment and server fan

Don't overload the cabinet by trying to fit in too many servers —75% to 80% of capacity is about right. Leave at least 1U of space between rows of servers for front-to-back ventilation. Maintain at least a 4 cm clearance between equipment and the front and back of the cabinet. And finally, ensure all unused cabinet space is closed off with blank panels to prevent mixing of hot and cold air.

You can increase ventilation even more by installing fans to actively circulate air through cabinets. The most common cabinet fans are top-mounted fan panels that pull air from the bottom of the cabinet or through the doors. For spot cooling, use a fan or fan panel that mounts inside the cabinet.

4 - Monitor temperature

To ensure that your components are operating within their approved temperature range, it's important to monitor conditions within your cabinets. The most direct method to monitor cabinet temperature is to put a thermometer into your cabinet and check it regularly. This simple and inexpensive method can work well for small installations, but it can't raise the alarm if the temperature goes out of range, and must be checked manually. Another simple and inexpensive addition to a cabinet is a thermostat that automatically turns on a fan when the cabinet's temperature exceeds a predetermined limit.

Many network devices come with SNMP or IP-addressable internal temperature sensors to tell you what the internal temperature of the component is. This is the preferred temperature monitoring method because these sensors are inside your components where the temperature really counts. Plus you can monitor them from your desktop—they'll send you an alert if there's a problem. There are also cabinet temperature sensors that can alert you over your network. Although these sensors only monitor cabinet temperature, not the temperature inside individual devices, these sensors can be a valuable addition to your cooling plan, especially for older devices that don't have internal sensors. View Black Box's AlertWerks Environmental Monitoring System for more information on cabinet-monitoring sensors.

Server Cabinet Cooling Solutions

Keeping your data and server cabinets cool doesn't have to be complicated. Just remember not to overcrowd the cabinets, be sure to provide adequate ventilation, and always monitor conditions within your cabinets. Black Box's Server Cabinet Cooling solutions ensure you protect your essential IT equipment with the highest-quality cooling solutions available, such as:

* Server Cooling Cabinets:

The ClimateCab™ IP52 / NEMA-12 Cabinet is the answer when you need to house servers or IT equipment outside the data centre, especially in harsh environments, and don't have a cooling infrastructure in place. The digitally controlled air-conditioning unit (from 2.950 to 8.530 BTU) keeps equipment cool, even with temperatures up to 55°C, and removes heat buildup by using closed-loop cooling. Sealed cable entries prevent air exchange with warm ambient air. Just install your equipment, plug in the AC unit, and you have a complete, self-contained, self-supporting micro data centre. No plumbing is needed as an internal evaporator eliminates condensation.

* Server Rack Fans:

Allow maximum airflow to your rackmount equipment with Black Box's fan trays. These fans are used to draw air upwards through the cabinet. Choose from roof-mounted fan trays, or rackmount fan trays that attach to the 19" rails of the cabinet.