Enclosures: Keep your cool

Enclosures: Keep your cool

Advances in technology have allowed equipment to become faster and more compact, but with smaller spaces, come higher temperatures. Can your data centre handle the heat?

The answer is, probably not. As equipment heats up, performance slows and productivity drops. Many companies don’t realise that excessive heat shortens the life of electronic equipment and can even shut it down permanently.

Heat may be invisible, but its effects are devastating and costly. According to the Uptime Institute, for every 10°C that internal cabinet temperatures rise above normal room temperature, the life expectancy of the enclosed electronics drops by 50%.

When it comes to protecting data centre servers, IT professionals should think inside the box and select data cabinets that are not only well built, but also help manage heat buildup.

Many existing data centres weren’t built to handle the thermal densities of newer networking equipment such as blade servers, which as an example, can produce 21 to 24 kilowatts of heat in a single cabinet.

Old habits die hard

Many organisations believe that simply cooling the ambient air to lower the inside cabinet temperature will keep the heat at bay. Yet while this approach seems logical, it is problematic. Issues still present are:

  • Continued hot spots and overheating.
  • Massive increases in energy costs.
  • Recirculation air flows are not addressed.
  • Using very cold air flows can cause condensation, leading to corrosion, equipment failure, poor or intermittent contacts, thermal expansion or contraction failures, etc.

The best way to measure the amount of heat produced in a cabinet is to measure the power being consumed. Every watt of power consumed nearly equals every watt of heat produced. The key to keeping equipment cool is channelling or ducting cool air into the equipment and providing a path for the heated air to escape out of the cabinet.

Cabinet design’s role in heat dispensation

Cabinets can be designed with features that facilitate heat dispensation and placed in a data centre to define specific thermal zones for air intake and exhaust to create maximum cooling efficiencies.

Passive cooling vs active cooling

Passive cooling uses louvers, vents and perforated panels, along with the equipment’s fans, to exchange ambient air. Active cooling uses cabinet venting fans to exhaust hot air and can be used in conjunction with piped-in chilled air.

What are the options?

There are three types of hot aisle/cold aisle cabinet designs, but which to utilise generally depends on the heat dispensation levels in your facility:

Hot aisle/cold aisle data centre layout

A hot aisle/cold aisle data centre layout has specific hot and cold areas. Computer room air conditioners (CRAC) are placed strategically to create cold aisles. The cabinets on both sides of those aisles have network equipment installed that draws the cold air through the cabinet fronts and into its intakes.

The equipment exhaust exits through the cabinet rear, creating hot aisles that alternate with the cold aisles. The hot air is then re-circulated to the CRAC unit. This air flow management strategy addresses adverse equipment air flow, preventing equipment exhaust from being drawn into other equipment intakes. This type of data centre layout has been universally accepted and is being actively deployed in most data centres.

Hot aisle/cold aisle configuration: Passive cooling

When hot aisle/cold aisle data centre cabinet positioning is implemented and heat buildup is 1,500 to 2,000 watts, passive cooling can be utilised. In this configuration, cold air is pulled from the floor to cool equipment as it moves from the front to the back of the cabinet. The resulting warm air is then exhausted out the cabinet top and back.

Hot aisle/cold aisle configuration: Active cooling

Hot aisle/cold aisle cabinet configurations in conjunction with active cooling, are the most efficient cooling solutions for components with heat dispensation levels ranging from 4,000 to 6,000 watts. Cabinets that have a perforated front and a rear fan door are the most efficient for this type of application.

Hot aisle/cold aisle configuration: Active cooling with floor ducting

Hot aisle/cold aisle cabinet configurations in conjunction with active cooling plus floor ducting, will help manage heat buildup when heat dispensation levels reach 6,000 to 10,000 watts. The most effective cabinets for these applications have a front window door, a rear fan door and a floor-ducted base with plenum front.

Lighten the load

Another popular solution for incorporating high density equipment into the modern data centre is load spreading. When the power required, and heat generated by the equipment inside a cabinet exceeds the cabinet’s cooling capacity, installing the equipment in multiple cabinets, or spreading the load, more evenly distributes the power and cooling demands between cabinets.

Within the data centre, many 1U servers and blade servers do not need to be installed in the same cabinet and can be spread out across multiple cabinets. Load spreading can be a good option, because it may be less costly to enlarge or expand a data centre than to add complex supplemental cooling systems.

It is worth noting that this method can result in a large amount of unused vertical space within cabinets. The unused space must be filled with blanking panels to prevent hot air recirculation, which reduces cooling performance.

Load spreading can also cause data cabling issues. However, regardless of the techniques implemented, the importance of proper cable management cannot be underestimated. Although cable spaghetti is the stuff of nightmares for IT professionals, it also restricts air flow and you guessed it, raises the temperature within the cabinet, as well as a plethora of other issues unrelated to heat.

Conclusion

Although cabinet design has a lot to answer for, it is important to remember that a cabinet, no matter how good the design, cannot make up for insufficient total cooling within the data centre. A cabinet can never cool itself below the surrounding ambient air temperature, but it can promote the efficiency of heat movement in the data centre via the control of air flow. Therefore, a combination of both efficient cabinet design, coupled with an efficient overall data centre cooling system is the way to go when it comes to keeping things cool.