Practice Exercise 1: PUE and DCIE

A Data Center has the following IT equipment on UPS:

o 30 x server cabinets each containing 12 x 3U servers

o Each server has dual 500W (nameplate rate*) PSs

o De-rate PS Nameplates by 0.60 for this exercise

o 10 disk array cabinets @ 5kW each (actual)

o 5 communications cabinets @ 3kW each (actual)

o 6 x CRAC units each draw 50kW to provide cooling to the facility

o The lighting load and all other misc. support systems, total 25 kW (not on UPS)

Questions:

A. What is the Category “0” PUE?

B. What is the Category “1” PUE? (Class Discussion)

C. Is this facility efficient? (Class Discussion)

D. What could be improved? (Class Discussion)

E. Bonus question: What is your Data center PUE? (Class Discussion)

1

Exercise 1: PUE and DCIE

Assume a Data Center which has a total facility power reading of 400kW

Within the computer room the following equipment is installed:

▪ 420 x 3U servers, and each server has dual 400W power supplies (actual running load),

▪ Power supplies are configured as active/active, and each capable of supporting the full load

▪ 10 disk array cabinets @ 5kW/ rack (actual) ▪ 5 Networking cabinets @ 4kW rack (actual)

The total UPS output reading is 250kW

Question 1: What is the PUE₁ value?

Question 2: What would the PUE₃ reading be?

Question 3: Due to the time of year, the air conditioning system is not at full capacity.

What would the impact be on the PUE₃ value if all 6 CRAC units in the room where fully operational, each

with a running load of 40 kW.

Question 4: What would the DCiE figure be when all AC units are running.

A. 33% - Very inefficient

B. 40% - Inefficient

C. 48% - Average

D. 65% - Very Efficient

E. 82% - Efficient

2

A 1.4 B 1.5

C 1.6

D 1.7

A 1.65 B 1.67

C 1.69

D 1.71

A 2.08 B 2.18

C 2.28

D 2.34

PUE DCiE Level of Efficiency

3.0 33% Very Inefficient

2.5 40% Inefficient

2.0 50% Average

1.5 67% Efficient

1.2 83% Very Efficient

Exercise 2 Planned Maintenance

Following the recommendations of the BICSI 002 Data Center Design & Implementation Best Practice document, a classification rating for a data center facility can be determined.

Defining Operational Requirements: Time available for planned maintenance

Operational

Level

Annual Allowable Planned

Maintenance hours

Description

0

>400

Functions are operational less the 24hrs/day and less than 7 days a week. Scheduled maintenance is available during normal hours

1

100 – 400

Functions are operational less the 24hrs/day and less than 7 days a week. Scheduled maintenance is available during normal hours

2

50 – 99

Functions are operational up to 24hrs/day and up to 7 days a week and up to 50 weeks/yr. Scheduled maintenance is available during normal hours

3

0 - 49

Functions are operational 24hrs/day, 7 days a week and 50 weeks or more a year. No scheduled ‘down’ time permitted during normal hours.

4

0

Functions are operational 24hrs/day, 7 days a week and 52 weeks or more a year. No scheduled ‘down’ time permitted during normal hours.

Allowable maximum annual downtime

(minutes)

Targeted Uptime

(%)

>5000 <99

500-5000 99 – 99.9

50 – 500 99.9 – 99.99

5 – 50 99.99 – 99.999

0.5 – 5.0 99.999 – 99.9999

Availability Ranking

By following the above tables and application procedure, determine the Classification Rating for the following

scenario.

You are undertaking a Business justification scenario and you need to determine what the best choice is for the company.

o Option 1: Conduct planned maintenance twice a year, and each maintenance window will be from 10 AM on Saturday to 2PM the following day.

o Option 2: Try to carry out all maintenance over one weekend period starting at 6PM Friday evening until 4PM Sunday.

In both scenarios the company will not accept more than 4 minutes unplanned outage per month.

The impact of any outage would be considered to be Enterprise wide.

For the following determine which option would be best for the business and please explain why.

Operational Level 500 – 5000 min 50 – 500 min 5.0 – 50 min 0.5 – 5.0 min

Level 1 1 1 2 3

Level 2 1 2 2 3

Level 3 2 2 3 4

Level 4 3 3 4 4

Classification Description – Impact of Downtime

Enterprise wide Affecting the quality of service delivery across the entire enterprise, or resulting in a significant disruption or delay in achieving key organisational objectives.

Multi Regional Affecting a major portion of the enterprise (although not in its entirety) or resulting in a major disruption or delay in achieving key organisational objectives

Regional Affecting a portion of the enterprise (although not in its entirety) or resulting in a moderate disruption or delay in achieving key organisational objectives

Local Affecting only a single site, or resulting in a minor disruption or delay in achieving key organisational objectives

Sub Local Affecting only a single function or operation, or resulting in a minor disruption or delay in achieving non- critical organisational objectives

Impact of

Downtime

Availability

Ranking 0

Availability

Ranking 1

Availability

Ranking 2

Availability

Ranking 3

Availability

Ranking 4

Enterprise wide Class F1 Class F2 Class F3 Class F4 Class F4

Multi Regional Class F1 Class F2 Class F3 Class F3 Class F4

Regional Class F1 Class F2 Class F2 Class F3 Class F3

Local Class F0 Class F1 Class F2 Class F3 Class F3

Sub Local Class F0 Class F0 Class F1 Class F2 Class F2

Question 1:

Assumption: Planned maintenance twice a year, each maintenance window from 10 AM Saturday to 2PM Sunday. The impact of any outage would be considered Enterprise wide, not more than 4 minutes of unplanned outage per month accepted. Determine the Classification Rating A. Class F1

B. Class F2

C. Class F3 D. Class F4

Question 2:

Assumption: Carry out all maintenance over one weekend period starting 6PM Friday until 4PM Sunday. The impact of any outage would be considered Enterprise wide, not more than 4 minutes of unplanned outage per month accepted.

Determine the Classification Rating A. Class F1 B. Class F2 C. Class F3 D. Class F4

Exercise 3 Site Location

Question 1:

Using the above maps, determine a suitable location to build a data center and list three reasons why:

1.

2.

3.

Exercise 4: Cabinets

Question 1:

Assuming a rack dimension of 24” x 42” (600mm x 1050mm), what would the optimum room layout dimensions be to

provide the largest number of cabinets, within a 350m² (3500 ft²) room.

A. 200

B. 204

C. 212

D. 220

Exercise 5: Floor Tile

Type A, airflow rated at ≈ 650 CFM

Type B, airflow rated at ≈ 700 CFM

Type C, airflow rated at ≈ 800 CFM

Type D, airflow rated at ≈ 1150 CFM

Type E, airflow rated at ≈ 1500 CFM

Question 1:

Using the formula Q = M x Cp x Δt, calculate the volume of air required to cool a 7kW rack, given that the Delta T

across the equipment is measured at 12°C.

Please select the most appropriate tile to use in this situation from the tiles specified below.

*To convert from m³/s to CFM multiply by 2120

A. Type A B. Type B C. Type C D. Type D E. Type E

Exercise Practice 6 Cooling

UPS Output = 500kW

Room Layout = 120 Cabinets

10 CRACs as shown

1. What is the minimum cooling capacity for each CRAC, specified in:

o BTUs

o kW

o Tons

2. CRAC ratings for a design of:

o N

o N+1

o N+2

3. What is the per cabinet average density?

Note: For this exercise ignore all other heat loads

4. Bonus question: What happens if one CRAC Fails?

Answers

Total IT Heat Load

o BTUs = (500kW x 3,413) = 1,706,500

o kW = 500

o Tons = 1,706,500 / 12,000 = 142.20

✔ Short cut = (500 / 3.5) = 142.85 Tons

✔ Note 3.516 rounded to 3.5

Each CRAC

o BTUs = 170,650

o kW = 50

o Tons = 14.2

CRAC ratings for a design of:

o N = 50 kW / 14.2 Tons each

o N+1 = 55.5 kW / 15.8 tons each

o N+2 = 62.5 kW / 17.8 Tons each

Average Rack Density = 500 kW / 120 = 4.16 kW

Exercise 6: Cooling

Assumptions

a. 10,000 ft2 (1000 m2) of raised floor with dimensions of 75’ X 134’ (23m x 42m)

b. The data center is designed as a Tier 2 facility

c. Twelve 20 Ton (70kW) sensible cooling units with 12,000 CFM (5.663 m³/s) of air flow each are installed(6 per side)

d. Cooling units are uniformly distributed along each of the long walls

e. Installed load is 350 kW which is concentrated in one end of room in an area of 75’x 67’ (23m x 21m);

the other half essentially is left empty

f. 300 perforated tiles are available for use, each rated at 750 CFM (0.354 m³/s) per tile

Question 1: How many cooling units are required to cool the load?

Question 2: How many cooling units are required to provide cooling and redundancy?

Question 3: How many perforated tiles should be installed?

Question 4: Which cooling units should be shut off?

A Top 6 units

B Bottom 6 units

C Right hand 6 units

D Left hand 6 units

A 5

B 6

C 7

D 8

A 5

B 6

C 7

D 8

A 60

B 80

C 100

D 150

E Alternate units around the room

E Alternate units around the room

Question 5: What is a potential problem with this layout?

A No problem with this design B

Cold air can drift under floor

C Hot air can drift around the room

D Adding more tiles will resolve the issue

Question 6: How do you resolve the potential problem?

A Blank off under the floor

B Blank off above the floor

C None of the above

Question 7: At what load should an additional cooling unit be activated?

Question 8: Assuming older technology with a Delta T of 10°C across the equipment, use the previously used airflow formula Q = M x Cp x Δt, to verify the result.

A 351

B 375

C 401

D 420

A 75

B 78

C 80

D 82

Exercise 7 UPS Question 1: From the previous exercise, calculate the UPS size required to support the Data Centre. Assume a 0.9 PF for the UPS with a maximum design utilization load of 80% and the potential for 100% growth within the space requirement.

A 500 kVA

B 750 kVA

C 900 kVA

D 1MVA

Question 2: Assuming a 35kW electrical load for each CRAC unit and a 0.8 PF, calculate the Standby Generator rating for this facility.

A 1,525 kVA

B 1,730 kVA

C 1,905 kVA

D 2,110 kVA

Question 3: Based on 540kWh per barrel of diesel and each barrel holding 159 litres, what size tank would be required to provide 72 hours of Generator backup.

A 30,000

B 35,000

C 37,500

D 40,000

Exercise 8

Question 1: Calculate the values for the missing items based on the information provided.

Team 1 Team 2 Team 3

Enterprise Data Center Co-location facility Social Media provider

Tier rating Ti

e

r

I

V

Ti

er

III

Ti

er

II

Power Draw 3

M

W

5

M

W

10

M

W

PUE 1.

7

1.

5

1.

3

Power/rack 6

k

W

4

k

W

8k

W

Rack density 2.4 m²/rack 3.2 m²/rack 2 m²/rack

UPS type On line static Line Interactive D

R

U

PS

Calculate No of racks Area for white space Redundancy level Size of UPS in kW