COMP 4923 A2 Data Center Cooling Danny Silver JSOCS, Acadia University

References Chapter 8 of The Greening of IT, by John Lamb, IBM Press, Calculating Requirements for Data Centers, by Neil Rasmussen, White Paper #25, American Power Conversion (APC), 2003.White Paper #25

Chilly Facts Breakdown of typical electrical power use in a data centre Power, cooling and lights = 50% of total data center energy use Cooling alone accounts for 37% of energy use Second largest energy cost for data centers – 3 MW IT data center, requires 6 MW power – $5.25M a $0.10 / KWH – 10% reduction in IT load = $260,000 savings – 30% reduction in cooling = $580,000 savings

Background All electrical equipment produces heat Must be removed to prevent failure/fatigue Air cooling is most common approach Heat is energy and is commonly expressed in Joules, BTU, Tons, or Calories Common measures of heat output (power): – BTU per hour – Tons per day – Joules per second = Watts

Background In North America, specifications for power and cooling capability often provided in the legacy BTU and Tons terms Always confusing … world is moving to Watts Conversion to Watts of power (energy / time):

Background The bad news: – Very little energy used to process bits – Most just produces the by-product of heat The good news: – This means that the thermal output of your data center (BTU per hour) = the AC electrical power consumed (Watts)

So What Creates the Heat? IT Equipment UPS – Uninterrupted Power Supply Power distribution system Lighting People

Simple Data Centre Worksheet Excel version of above table.

Question Dalhousie has a 2500 sq. ft data center with a 100KW power supply. There are 400 servers in the data center that use about 150 watts max each. A maximum of 10 people work in the data center. Assume that on average the data center is working at 35% capacity. What is the thermal output of the data center (ie. how many Watts of cooling are needed)?

Question Google has a 10,000 sq. ft data center with a 400KW power supply. There are 1600 blade servers in the data center that use about 40 watts max each. A maximum of 25 people work in the data center. Assume that on average the data center is working at 45% capacity. What is the thermal output of the data center (ie. how many Watts of cooling are needed)?

Thermal Output of a Typical Data Center

Video Cooling a data centerhttp:// f8WqyQPushttp:// f8WqyQPus

Strategies for Increasing Data Centre Cooling Meter your data center energy use (IT, cooling) – You can reduce if you do not measure Bring cooler closer to heat source Properly seal data center Optimizing air flow Use variable capacity cooling systems to increase efficiency Place lights on motion detector switches Turn off chillers in the winter, use outside air

Strategies for Increasing Data Centre Cooling Properly seal data center – Keep all doors closed at all times to maintian cool air and low humidity (should be 40-55%) – Seal all cable openings – Major reason for container approach Optimizing air flow – Goal is to move max air away from equipment – Optimize rack configuration, air conditioner placement, cable management – Use hot and cold aisles

Strategies for Increasing Data Centre Cooling Use economizer and variable capacity cooling systems to increase efficiency – Use outside air in winter months (direct use of cool air, or use of cool air to chill A/C) – Variable number of refrigeration compressors – Digital Scroll compressor technology best

Solutions Fuel cells – replacing backup diesel generators with hydrogen-powered fuel cells Embedded cooling – Liebert XD rack-level method - removes heat before it leaves the rack Chip-level cooling – chips manufactured with cooling systems embedded – Chilled water:

Future Solutions Google Data Centers – Container based – Typical – Amazing floating data centers Facebook Data Center – Put your Data Center in Iceland:

Resources 2011 best practices: bestpractices.pdf bestpractices.pdf