Free Cooling: the Server Side of the Story
by Johan De Gelas on February 11, 2014 7:00 AM EST- Posted in
- Cloud Computing
- IT Computing
- Intel
- Xeon
- Ivy Bridge EP
- Supermicro
Benchmark Configuration
Since Supermicro claims that these servers are capable of operating at inlet temperatures of 47°C (117 °F) while supporting Xeons with 135 W TDPs, we tested with two extreme processors. First off is the Xeon E5 2650L at 1.8GHz with a low 70W TDP and a very low Tcase of 65°C. It's low power but is highly sensitive to high temperatures. Second, we tested with the fastest Xeon E5 available: the Xeon E5 2697 v2. The TDP is 130W for 12 cores at 2.7GHz and Tcase is 86°C. This is a CPU that needs a lot of power but it's also resistant to high temperatures.
Supermicro 6027R-73DARF (2U Chassis)
| CPU |
Two Intel Xeon processor E5-2697 v2 (2.7GHz, 12c, 30MB L3, 130W) Two Intel Xeon processor E5-2650L v2 (1.7GHz, 10c, 25MB L3, 70 W) |
| RAM | 64GB (8x8GB) DDR3-1600 Samsung M393B1K70DH0-CK0 |
| Internal Disks | 8GB flash disk to boot up, 1 GbE link to iSCSI SAN |
| Motherboard | Supermicro X9DRD-7LN4F |
| Chipset | Intel C602J |
| BIOS version | R 3.0a (December the 6th, 2013) |
| PSU | Supermicro 740W PWS-741P-1R (80+ Platinum) |
All C-states are enabled in both the BIOS and ESXi.
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ShieTar - Tuesday, February 11, 2014 - link
I think you oversimplify if you just judge the efficiency of the cooling method by the heat capacity of the medium. The medium is not a heat-battery that only absorbs the heat, it is also moved in order to transport energy. And moving air is much easier and much more efficient than moving water.So I think in the case of Finland the driving fact is that they will get Air temperatures of up to 30°C in some summers, but the water temperature at the bottom regions of the gulf of Finland stays below 4°C throughout the year. If you would consider a data center near the river Nile, which is usually just 5°C below air temperature, and frequently warmer than the air at night, then your efficiency equation would look entirely different.
Naturally, building the center in Finland instead of Egypt in the first place is a pretty good decision considering cooling efficiency.
icrf - Tuesday, February 11, 2014 - link
Isn't moving water significantly more efficient than moving air because a significant amount of energy when trying to move air goes to compressing it rather than moving it, where water is largely incompressible?ShieTar - Thursday, February 13, 2014 - link
For the initial acceleration this might be an effect, though energy used for compression isn't necessary lost, as the pressure difference will decay via motion of the air again (but maybe not in the preferred direction. But if you look into the entire equation for a cooling system, the hard part is not getting the medium accelerated, but to keep it moving against the resistance of the coolers, tubes and radiators. And water has much stronger interactions with any reasonably used material (metal, mostly) than air. And you usually run water through smaller and longer tubes than air, which can quickly be moved from the electronics case to a large air vent. Also the viscosity of water itself is significantly higher than that of air, specifically if we are talking about cool water not to far above the freezing point of water, i.e. 5°C to 10°C.easp - Saturday, February 15, 2014 - link
Below Mach 0.3, air flows can be treated as incompressible. I doubt bulk movement of air in datacenters hits 200+ Mphjuhatus - Tuesday, February 11, 2014 - link
Sir, I can assure you the Nordic Sea hits ~20°C in the summers. But still that tempereture is good enough for cooling.In Helsinki they are now collecting the excess heat from data center to warm up the houses in the city area. So that too should be considered. I think many countries could use some "free" heating.
Penti - Tuesday, February 11, 2014 - link
Surface temp does, but below the surface it's cooler. Even in small lakes and rivers, otherwise our drinking water would be unusable and 25°C out of the tap. You would get legionella and stuff then. In Sweden the water is not allowed to be or not considered to be usable over 20 degrees at the inlet or out of the tap for that matter. Lakes, rivers and oceans could keep 2-15°C at the inlet year around here in Scandinavia if the inlet is appropriately placed. Certainly good enough if you allow temps over the old 20-22°C.Guspaz - Tuesday, February 11, 2014 - link
OVH's datacentre here in Montreal cools using a centralized watercooling system and relies on convection to remove the heat from the server stacks, IIRC. They claim a PUE of 1.09iwod - Tuesday, February 11, 2014 - link
Exactly what i was about to post. Why Facebook, Microsoft and even Google didn't manage to outpace them. PUE 1.09 is still as far as i know an Industry record. Correct me if i am wrong.I wonder if they could get it down to 1.05
Flunk - Tuesday, February 11, 2014 - link
This entire idea seems so obvious it's surprising they haven't been doing this the whole time. Oh well, it's hard to beat an idea that cheap and efficient.drexnx - Tuesday, February 11, 2014 - link
there's a lot of work being done on the UPS side of the power consumption coin too - FB uses both Delta DC UPS' that power their equipment directly at DC from the batteries instead of the wasteful invert to 480vac three phase, then rectify again back at the server PSU level, and Eaton equipment with ESS that bypasses the UPS until there's an actual power loss (for about a 10% efficiency pickup when running on mains power)