Connecting Networks

Heat wave: why French DCs are holding up

Heat episodes are not taken lightly by data center operators. In France, "we have gone from 40 degrees to 46 degrees in a few years. We have met the specifications of Spain," says Marie Chabanon, Technical Director of DATA4 Group.


In order to counter any heat stroke, the datacenters' resistance to temperatures has increased " The great fear is the domino effect [...] If all or part of the cold infrastructure has problems, it affects the rest of the equipment. And if the refrigeration unit stops, it's the worst thing that can happen to us with the complete power outage," added Fabrice Coquio, Interxion's Managing Director. A risk also linked to the quality of RTE or Enedis' electricity distribution. "We must anticipate a risk of electrical loss or incident," explains Marie Chabanon.


But data center operators have a secret boot to fight this domino effect. "Data center electrical systems are built to be 100% operational. However, this is never the case. The consequence is that in the event of a load, such as a higher cold demand, we have unallocated power that we can use," explains Fabien Gautier of Equinix. This is called capacity redundancy.


Especially since the densification of computing power per unit of space in recent years, with the democratization of virtualization, has led to more consumption and more heat. "With 14 or 15 kvA berries, we cause hot spots, which are more sensitive to heat waves," explains Fabien Gautier. The work of urbanizing the IT architecture deployed in the rooms is therefore essential. "Our work is therefore the urbanization of the rooms. If they were completed on the fly, that can be a problem," he adds.

This involves, among other things, load balancing. "Our data centers are designated with redundancies and a 50% load rate. The backup machines will be used to provide additional power" in the event of a heat wave, says Marie Chabanon. Nevertheless, it must be anticipated. "We must ensure that backup systems are ready to be operational, through maintenance and control actions on backup equipment."


The protection of data centers against heat also requires the installation of curative systems. "We installed water spray systems to water the roof equipment with water that is not too cold," says Fabrice Coquio.

And to be prepared for any eventuality in the early evening, the schedule of the technicians present on site has been modified. It is also necessary to warn customers so that they are careful.


Recent advances in hardware strength and data center design have made it possible to increase the temperatures in server storage rooms. "The idea is that the lower the PUE (Power Usage Effectiveness), the better it performs. Ten years ago, we used to make datacenters where it was difficult to achieve a PUE of 1.6. Today we are at 1.2 and we are getting closer to 1, which represents 20% savings by playing on the temperature and energy performance of the new equipment," says Marie Chabanon. As a result, the cooling system now focuses on machines with forced air. There is no longer any need to refrigerate entire rooms.

"We are seeing an evolution in the design of indoor temperature according to the recommendations of the Ashrae (American Society of Heating and Ventilating Engineers). The idea is to work well with much higher temperature ranges. We have gone from 20 to 22 degrees to 18 to 27 degrees," she adds. Since 2011, these standards have been raised: they recommend blowing at 26 degrees on the front panel on indoor equipment. "The humidity level was also modified [...] In 2008, it was between 40 and 60%. It is now 70%," says Fabrice Coquio.


This will limit cooling costs without affecting the resistance of the installations. A critical point in hot weather.





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Source : ZDNet





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