Facebook Data Center Design/Operations Improvements by Tom ...

Forest City, NC

Lessons Learned - Electrical

In-rush Current with PSU• Higher in-rush current experienced under repeatedpower outage• CB see the high in-rush and trip on GF• Cause due to NTC resistor characteristics• Adjusted setting accordingly to resolve issue

In-rush Current with PSU

Lessons Learned - Mechanical

PUE Update for PrinevillePUE Data: Trended each minute; for period 14 Apr, 2011- 15 Jun, 2011

Lessons Learned• Controls issues with a 100% OA economization withdirect evaporative cooling• We found an error in the controls sequence during highhumidity levels within the datacenter that turned a singlepass system into a recirculating system by closing theoutside air dampers 100%• Control loop tuning (14) independently controlled AHU lineups has posed challenging issues to controllingtemperature and humidity during large swings betweenday and night during the summer season

Lessons Learned• WUE has not been reported as we are verifyingreadings. The original system wasn’t designed tocalculate WUE as the design were complete in late2009, WUE was created in March of 2011 by TheGreen Grid.• A perforated target plate is for improved air distributionwithin the datacenter is in review

Next Steps - Mechanical

Datacenter Basis of Design Comparison80ºF inlet85ºF inlet85ºF inlet65% humidity80% humidity90% humidity20ºF ΔT 35ºF ΔT 35ºF ΔTPRN1A1BPRN1C1DFRC1A1B

From Prineville to Forest City-45%air handlinghardware

Psychrometric Chart – PRN1A1B• 65F – 80F cold aisletemperature• 65% relativehumidity max• 41.9F min dew pointtemp• 105F Dry Bulb /70.3F Wet Bulb• Summer: 110ºFDB,70.3ºFWB

Psychrometric Chart – PRN1C1D• 65F – 85F cold aisletemperature• 80% relative humiditymax• 41.9F min dew point temp• 35F delta T acrossservers allowed tominimize fan arrays from(14) to (8)• We reduced the evap pumpskid redundancy from 2Nto N• 105F Dry Bulb / 70.3F

Psychrometric Chart – FRC• 65F – 85F cold aisletemperature• 90% relative humiditymax• 41.9F min dew pointtemp• DX added for extremeweather criteria in tocondition the airwithin acceptableserver conditions• 35F delta T acrossservers allowed tominimize fan arraysfrom (14) to (8)• Also reduced the evappump skid redundancy

Questions?