How to Fix Hot Spots in the Data Centre

Eliminiating hot spots in the Data Centre is a challenge that most operators face at some point. If hot spots are allowed to continue for an extended period of time, they pose a serious threat to not only IT equipment reliability and performance, but can also invalidate the warranties or maintenance agreements of hardware manufacturers.

To avoid these risks data centre operators may choose to take actions such as lowering the cooling unit set point, placing perforated tiles in the hot aisle, and placing pedestal fans in front of the problem racks. These actions may fix the problem temporarily, but could also result in an energy penalty or even create more hot spots elsewhere in the data centre.

To fix a hot spot you first have to define what a hot spot is and understand what causes them. In many cases a hotspot is not created by a lack of cooling capacity in the data centre. Identifying the cause enables you to improve the effectiveness of your existing cooling whilst simultaneously getting other benefits such as improved energy efficiency and avoiding the capital expense of adding more cooling units.

A hot spot is not any random hot temperature inside of a data centre. A hot spot is a location at the intake of IT equipment where the measured temperature is greater than the expected value. Hot spots occur most often towards the top of a rack.

The two main causes of hot spots are bypass and recirculation. Completely eliminating bypass and recirculation means that the hot and cold air streams are entirely separated which means no hot spots can exist.

Here are 4 simple steps you can take that will help eliminate hot spots without breaking your budget!

Manage airflow in the rack

Many hot spots appear due to hot exhaust air recirculation inside or around the rack. Therefore improving rack airflow management plays an important role in fixing hot spots. Open rack “U” spaces and cable penetrations are a common cause of hot exhaust air recirculation, which results in hot spots. Using blanking panels to fill the unused “U” positions and brush strip for cable penetrations in racks or enclosures is one of the most simple and cost effective methods for improving airflow in the rack.

Manage airflow in the room

After improving airflow management in the rack, the next important step is to improve airflow management in the room. To begin, seal all openings in the raised floor. Brush strips should be used to seal cable cutouts behind racks and under PDUs. These openings cause the majority of unwanted air leakages. Seal gaps around cooling units and other floor penetrations with air dam foam or pillows, replace missing floor tiles with solid tiles, and identify perforated tiles that are a source of bypass air and replace them with solid tiles. For example, if the tile is placed in front of an empty rack, replace it with a solid tile. Proper tile placement coupled with sealed gaps in the raised floor will reclaim lost cooling capacity.

Relocate problem loads

Relocating problem loads addresses hot spots by identifying the “problem” load and moving it to a lower-density rack. Provide the room with the capability to power and cool to an average value below the peak potential enclosure value, and spread out the load of any proposed enclosures whose load exceeds the design average value by splitting the equipment among multiple rack enclosures. Note that spreading out equipment among multiple racks leaves a sizable amount of unused vertical space within the racks. This space must be filled with blanking panels to prevent degradation of cooling performance. If it is possible to take down a server or other critical piece of equipment, this practice can fix a hot spot with little expense.

Thermal Containment

Another contributor of hot spots is the hot and cold air mixing that occurs over the tops of racks and around the end of racks. A key best practice is to separate the hot and cold air streams by containing the aisle and/or the rack. Containment not only helps to fix hot spots, but also provides the added benefit of energy savings over traditional uncontained data center designs.

Hot spots can result in poor server reliability, performance, or even server damage. These simple, inexpensive actions will help you to improve the efficiency and effectiveness of your data centre cooling, prolong the life of your IT equipment and avoid downtime.

If you’re having a problem with hot spots in your data centre or would like some advice about Data Centre Cooling strategies contact one of our team today.