Colocation Facility Guidelines for Deployment of Open Racks, Revision 4.0 (15 December 2020)

Overview

The sub-project began in 2016 to define what a colocation facility must provide for an Open Compute Open Rack, and Revision 4.0 is the December 2020 final. The 'Acceptable' level is the minimum must-have set, assumed to be reachable by up to 80% of existing colo facilities, for a rack weighing up to 500 kg with a maximum IT load of 6.6 kW. The 'Optimum' level is a more future-proof set for a rack up to 1,500 kg and 36 kW. The text cross-refers to an OCP Ready Requirements Matrix in Appendix F, and the document doubles as a primer for those unfamiliar with Open Compute hardware. Chapters cover data center access, white space, electrical, cooling and cabling.

Access and structure are treated first. The optimum building access is a loading dock with an integral lift or leveller, and delivery pathways need about 0.5 m of extra height above a 2.21 m (87 in) Open Rack v2 on castors because racks are bolted to pallets. Optimum pathway dimensions are at least 2.7 m high by 2.4 m wide, and corridors and white space need floor ratings of 567 kg (Acceptable) or 680 kg (Optimum) rolling and concentrated load and uniform loads of 732 kg/m2 (150 lb/ft2) or 1,221 kg/m2 (250 lb/ft2). Ramps, goods lifts of 500 or 1,500 kg and door sizes are specified, and ramps run 1:8 to 1:12 at the Acceptable level.

Electrical requirements distinguish 1N (Acceptable) from 2N A+B feeds (Optimum). The circuit capacity at the Acceptable level is 3-phase 16 A at 230 V or 30 A at 208 V for a 6.6 kW power shelf, and 3-phase 32 A at 230 V or 60 A or 50 A at 208 V at the Optimum level, which serves a 12.5 kW shelf, or dual circuits for a 25 kW shelf. Optimum voltage is 480/277, 400/230 or 208 VAC, with overhead circuit receptacles and both UPS and non-UPS feeds. Rack-based batteries are Allowed at Optimum, and generator load acceptance should be under 90 seconds (Acceptable) or 60 seconds (Optimum), within the battery backup unit hold-up time. Pod architecture shares infrastructure such as an RPP, containment and cabling pathways.

The cooling chapter specifies front-to-back airflow, hot and cold aisle containment, minimum cold aisle widths of 1,200 mm (Acceptable) or 1,500 mm (Optimum), maintenance aisles of 900 or 1,200 mm, and maximum rack density of at least 8 kW or 12 kW. Inlet air should meet ASHRAE Recommended (Acceptable) or Class A1 Allowable (Optimum), the Optimum air quality is EN 779 G4 and F7 filtration with gaseous and particulate monitoring, and temperature rise across racks is at least 8 °C or 12 °C. Cabinet blanking is recommended or mandatory. A delta T mismatch can starve IT of airflow. The document pre-dates the dominance of Open Rack v3 and uses 2020-era ASHRAE references.

Key points

1. 'Acceptable' assumes up to 80% of existing colo facilities can host a rack weighing up to 500 kg with up to 6.6 kW; 'Optimum' covers up to 1,500 kg and 36 kW.
2. Delivery paths need about 0.5 m (20 in) of extra height above a 2.21 m (87 in) Open Rack v2 on castors, because racks travel bolted to pallets.
3. Floor loading: rolling and concentrated load of at least 567 kg (Acceptable) or 680 kg (Optimum); uniform load of 732 kg/m2 (150 lb/ft2) or 1,221 kg/m2 (250 lb/ft2).
4. Goods lifts must carry at least 500 kg (Acceptable) or 1,500 kg (Optimum); ramp gradients are 1:8 to 1:12 at the Acceptable level.
5. Electrical redundancy is 1N at Acceptable and 2N (A+B) at Optimum; circuit capacity ranges from 3-phase 16 A/230 V to 32 A/230 V (or 60 A/208 V).
6. A 6.6 kW power shelf is served at the Acceptable level; the Optimum level serves 12.5 kW shelves, or dual circuits for a 25 kW shelf.
7. Generator load acceptance time is under 90 seconds (Acceptable) or under 60 seconds (Optimum), within battery backup hold-up time.
8. Maximum rack density is at least 8 kW (Acceptable) or 12 kW (Optimum); cold aisle width is at least 1,200 mm or 1,500 mm.
9. Rack temperature rise is at least 8 °C (Acceptable) or 12 °C (Optimum); 12 °C (53.6 °F) is the common industry design value.
10. Inlet air is ASHRAE Recommended (Acceptable) or Class A1 Allowable (Optimum); blanking panels are recommended or mandatory.

Using it in design

• Check the delivery route against rack height plus 0.5 m, door and corridor widths, and the lift capacity, before agreeing to host or design for Open Racks.
• Verify white space and corridor floor ratings for rolling, concentrated and uniform loads against the 500 kg and 1,500 kg rack classes.
• Size power circuits, voltage, receptacle type and A+B feeds to the power shelf rating, and confirm generator transfer time against battery hold-up.
• Declare the design delta T for the white space and compare it with the IT equipment's delta T, because a mismatch can cause airflow shortfall at full power.
• Set aisle widths of 1,200 to 1,500 mm cold and 900 to 1,200 mm hot or maintenance, and provide containment and mandatory blanking where the Optimum level is targeted.
• Use the matrix as a self-assessment checklist and recognise that it was written around Open Rack v2.

Who should read it

Colocation providers and their designers who want to host Open Racks, and OCP users assessing whether a facility is suitable for their deployment.

Document contents

1. Revision History
2. Scope
3. License
4. System Overview
5. Data Center Access
6. Vehicular Access
7. Delivery Pathway
8. Open Rack Packaging
9. IT Technical Space (White Space)
10. Pod Architecture
11. Electrical Systems
12. Cooling System
13. Air Containment Methods
14. Maximum Rack Density
15. Cold and Hot Aisle Widths
16. Inlet Air Conditions
17. Air Quality
18. Temperature Rise
19. Cabinet Banking of Open Space
20. Telecommunication Cabling, Infrastructure, Pathways and Spaces
21. Appendix F. OCP Ready Requirements Matrix

Read the document

Publication details

Authors

Mark Dansie; Stijn De Kruijf; Sean Halpin; Gerard Thibault; Brevan Reyher; Rob Coyle

Publisher

Open Compute Project Foundation

Year

2020

Document language

English

Source type

Industry body

Access

Open licence — downloadable

Licence

CC BY-SA 4.0 — share with attribution under the same licence

Licence evidence

www.opencompute.org

Citation