Myths of Data Center Containment: What’s True and What’s Not Lars Strong, P.E., Upsite Technologies Airflow Management Awareness Month June 8, 2016
Myths of Data Center Containment: What’s True and What’s Not
Lars Strong, P.E., Upsite Technologies
Airflow Management Awareness Month
June 8, 2016
Why Airflow Management
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Total Load
IT LoadPUE =
Mechanical plant + cooling fans: 35% of total load, 73% of non IT Load
2002 Uptime Institute Research
Bypass Airflow* 60%
Hot Spots 10%
Cooling Capacity 2.6x
2013 Upsite Technologies Research
Bypass Airflow* 48%
Hot Spots 20%
Cooling Capacity 3.9x
*More accurately, “Raised Floor Bypass Open Area” in today’s terminology.
The State of Airflow Management
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Raised floor
area (sq ft)
# of running cooling units
Raised floor
bypass open
area (%)
Hot spots (%
of cabinets
)
Cold spots (%
of cabinets) (Data from 6 sites)
Proper perforated tile
placement (%)
Cooling Capacity Factor (CCF)
Averages 7,527 8 48% 20% 35% 77% 3.9Minimum 720 2 13% 0% 0% 7% 1.2Maximum 37,00
040 93% 86% 86% 100% 32.0
Recommended
n/a n/a <10% 0% 0% 100% 1.2Conclusion: Inefficient cooling configuration / airflow management is the problem; capacity is not the problem.
Research
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Large unsealed cable openings can release ¼ of a cooling units capacity.
Raised Floor Open Area
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Raised floor openings sealed with KoldLok brush grommets
Raised Floor Open Area
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IT Intake Air Temperatures are Paramount
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Airflow is invisible Cooling capacity is difficult to quantify Mixed messages in the market Vendor influence Lack of education
Why are Myths Prevalent
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• Money
• OpEx Savings• CapEx Savings
• Capacity• Cooling Capacity
• IT Reliability
• Green Initiatives• CO2 Reduction
A 4,000 Sq. Ft. data center could reduce its operating expense by $60,000 annually, simply by improving airflow management.
AFM Problems Are an Opportunity
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“Containment eliminates bypass airflow”
• Bypass airflow – any conditioned air that does not pass through IT equipment before returning to a cooling unit.
Myth #1
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Bypass Airflow Clarified
Typical existing conditions
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Bypass Airflow Clarified
After raised floor AFM improvements
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Bypass Airflow Clarified
With Containment
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Bypass Airflow Clarified
Optimized
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“Containment improves efficiency / reduces costs”
• Only true if reduction of hot spots reduce IT equipment fan speeds
• Creates the opportunity to improve efficiency and reduce costs
Myth #2
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Stranded Capacity of low temperature set pointsLiebert DX Model VH267W 20-Ton Cooling Unit
Environmental Condition
Total(kW)
Latent(kW)
Sensible(kW)
72°F, 45% Rh 67.0 0 67.070°F, 48% Rh 64.5 4.8 59.7Stranded 2.5 4.8 7.3Stranded (%) 4% 11%
Stranded Capacity
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Stranded Capacity from low temperature set pointsLiebert Chilled Water Model 600C CRAH Unit
Cooling capacity increase from 7°F return air increase
Environmental Condition
Total(kW)
Latent(kW)
Sensible(kW)
72°F, 45% Rh 98.0 0 98.065°F, 45% Rh 70.0 0 70.0Stranded 28.0 0 28.0Stranded (%) 40% 40%
Stranded Capacity
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“When containment is deployed, perforated-tile placement doesn’t matter”
•There can be too many perforated tiles or grates in a cold aisles
Myth #3
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Misplaced/Excessive Supply Tiles
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“Containment increases the return air temperature to cooling units”
•Thermostat controls return air temperature
•Same flow rate and heat load so same average delta T
Myth #4
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Bypass Airflow Revealed
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“Full containment is essential, partial containment doesn’t work.”
• Doors alone can produce significant benefits• Sealing rack openings can make an impact• A few baffles can eliminate isolated hot spots
Myth #5
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Full containment didn’t solve intake air temperature problems
Hot and cold spots are still present
Myth #5
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Rack AFM is crucial to any aisle level solution
Myth #5
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Rack AFM is crucial to any aisle level solution
Myth #5
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No Containment
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Baffles and Doors
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Modular Containment
Modular Containment
Cold Aisle Application
Hot Aisle Application
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Modular Containment
Angled Rack Top Baffles (Cold Aisle)
Adjustable Rack Gap Panel
Vertical Rack Top Baffles (Hot Aisle)
Modular Containment
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Identify Your Opportunity
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There are two types of computer rooms
1. Those without IT equipment intake air temperature problems
• Improving AFM enables them to be more efficient
2. Those with IT equipment intake air temperature problems
• Improving AFM solves intake air temperature problems (hot
spots and cold spots) and enables them to be more efficient
• More efficient results in: lower OPEX, deferred CAPEX,
increased cooling capacity
A metric Upsite Technologies developed to estimate the utilization of computer room cooling infrastructure.
CCF is a ratio of the total rated cooling capacity to estimated heat load.
The Cooling Capacity Factor (CCF)
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Convert the total rated (stated) cooling capacity to kW, divide by 110% of the IT critical load (kW)
7 – 30 ton cooling units (210 tons) UPS load 235 kW
Total rated cooling capacity (210 tons x 3.52) = 739 kW
110% of the IT critical load (235 x 1.1) = 259 kW
CCF = 2.8 (739/259) Running cooling capacity is 280% of the load
CCF: How It’s Calculated
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CCFTons x 3.52 = kWcCooling unit capacityRated capacity at standard conditions (75 deg F, 45%Rh)Capacity goes up with increase in return temperatureCapacity goes down with decrease in return temperature
At 80% fan speed80% airflow volumeOnly 50% of fan energy
Identify Your Opportunity
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Relationship BetweenFlow rate : Delta T : Heat load
CFM =
q = amount of heat transferredCp = specific heat of airΔT = temperature rise of air across the heat source W = mass flow
CFM = cubic feet per minute of airflow through the server3.16 = factor for density of air at sea level in relation to F⁰ΔT = temperature rise of air through the server in F⁰
q = Cp x W x ΔT
3.16 x W Delta T
Heat Transfer Equation
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Relationship BetweenFlow rate : Delta T : Heat load
“Blade” servers at 35 F ⁰ ΔT consume 90 CFM / kW
“Pizza box” servers at 20 F ⁰ ΔT consume 158 CFM / kW
UPS load (kW) x CFM/kW = Total IT CFM
Typical IT Cooling Airflow Rates
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Key Airflow Management Metrics
AFM Metrics
IT Equipment Intake Air Temperature Cooling Capacity Factor (CCF) Raised Floor Open area Supply Tile Placement (perforated tiles and grates) Blanking Panel Utilization Bypass Airflow
A holistic approach An iterative process ‘Check in’ at the room level
after making any AFM improvements
Watch video at:upsite.com/resources/airflow-management/
Upsite’s 4 R’s of Airflow Management™
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June 15: How IT Decisions Impact Facilities: The Importance of Mutual UnderstandingPresented by Ian Seaton and Lars Strong, P.E.
June 22: The 4 Delta T’s of Airflow ManagementPresented by Lars Strong, P.E.
Register at upsite.com/airflow-management-awareness-month
Upcoming Webinar Schedule
Thank you!
@UpsiteTech
blog.upsite.com
On LinkedIn
Lars Strong, P.E.Senior Engineer, Upsite [email protected]
Follow Upsite for the latest news and information on data center AFM.