FAQ

How is the cooling system implemented?

• The back of the racks form a 'hot aisle', sealed from the rest of the data-center. The hot air flows directly to the outside of the data-center.
• The front of the racks are in an area that is constantly supplied with a mixture of outside air and air that is fed back from the hot aisle. The mixing is to prevent too low operating temperatures in winter. A control system maintains this area at 21 degrees °C.
  When Relative Humidity is >80% inside temperature is raised by mixing with exhaust hot air.
  When Relative Humidity is <10% inside temperature is lowered by reducing mixing.
• An independent control system keeps the pressure in the data-center at or slightly under ambiant pressure (-1 Pascal). Otherwise the server fans would have to overcome the pressure drop due to the outside air filters. This relief of pressure drop consumes approximately 400 Watts.
• The mixing and pressure principle: Mixing and Pressure

What is ETSI?
Full free air cooling can not be used with arbitrary equipment. The systems in the racks must be designed to operate at higher temperatures and Relative Humidity ranges than normally prescribed for data centers. We use systems that are compliant to the ETSI EN 300 019-1-3 V2.2.2 (2004-07) class 3.1 : Environmental Engineering (EE) Environmental conditions and environmental tests for telecommunications equipment; Part 1-3: Classification of environmental conditions; Stationary use at weatherprotected locations.   http://pda.etsi.org/pda/queryform.asp.
Class 3.1 requires that the environment stays within 10-35 degrees for 90% of the time. During 10% of the time, 5-40 degrees are allowed, and during 1% of the time -5 to 45 degrees are tolerated.

Can this concept work anywhere in the world?
The proof of concept was done in Scotland for practical reasons. Evidently, other geographies have a different climate. Historical weather data indicate that the Class 3.1 conditions will be respected in Brussels. Over the recent years, 2006 was the warmest with a peak temperature of 36.2 degrees C and 11 days where the peak temperature was above 30 degrees. (In 2007 it was 30.9 degrees during 2 days).
The results of this test are watched by the members of ETNO (_http://www.etno.be/_), the European Telecommunications Networks Operators' association. In the majority of the European countries the FFAC concept can be used.

Which systems can be used in a FFAC environment?

For the proof of concept, we used Sun Microsystems NETRA servers and storage trays. These servers are built with standard AMD, Intel and SPARC processors and are explicitly certified for ETSI Class 3.1. The Cisco switches are not ETSI Class 3.1 certified but can operate at 35 degrees long term. With this equipment, a FFAC data center can be operated today.
Sun and Cisco are not the only vendors supplying ETSI Class 3.1 compliant data centre equipment. With this project we want to raise interest for FFAC and stimulate ETSI Cllass 3.1 certification by IT manufacturers.

What was the actual setup?

Rack 1 : 14 x Netra X4100 server with 2 dual core 2.2 GHz AMD processor and 8 GB of memory
Rack 2 : 14 x Netra T2000 server with 1 eight-core UltraSPARC T1 processor and 8 GB of memory
Both racks have two STK 6140 storage trays with 2 TB of disks each and a Cisco 48 port C4948 Gb Ethernet switch.

What is PUE?

PUE (Power Usage Effectiveness) is the ratio of total energy consumption (servers + cooling) to 'useful' energy consumption (servers only).
During our test, the IT equipment is consuming 8240 Watts. The total power, including the FFAC fans and control system is 8680 Watts. The PUE is 8680/8240 = 1.055. A PUE of 2 is an accepted industry average for data-centers.
More info on Data Centers metrics: http://www.thegreengrid.org/gg_content/Green_Grid_Metrics_WP.pdf

Will the impact of incoming dust on the reliability of data center equipment be tested?
Outside Air is filtered with G4 filters. These filters guarantee > 90% dust capturing. Experience proves that this keeps the environment within ETSI 300-019 : art 5.4. ( Sand < 30mg/m³, Dust(suspension) < 0.2 mg/m³, Dust (sedimentation) < 1.5 mg/m²h) . Maximum pressure drop is 250 Pascal. Filters will have to be replaced aproximately 2 times / Year depending on outside conditions.

Are the specific truck layout plans and calculations available?

• Some pdf-views: View1, View2, View3
• The Auto Cad lay-out:Truck Auto Cad
• The electrical scheme: Electrical_Scheme
• Sensors: Pressure, Temp_RH
• Ventilator and Frequency Regulator: Ventilator, Frequency_controler
• The calculations: Calculatios
• Some Pictures of the construction: Construction_1Construction_2

 Adittional truck design information can be obtained from Johan.Vanderhaegen@Belgacom.be

Are Historical Data available for download ?

Next .xls contains manually collected data on Temperature, Relative Humidity, Power consumption and PUE: Results

Will the Belgacom-Sun FFAC truck travel to other locations in Europe?

There are currently no plans to position the truck in other European locations