How to improve cooling efficiency of server rooms without cold-aisle/hot-aisle arrangement?

Data center cooling
Data center design
Hi, I was given server rooms where server racks are placed front-to-back without cold aisle and hot aisle. The racks are of mixed brands. I approached our APC rep and was advised to change the racks to APC racks and install back rack doors with exhaust fans as such add-ons are only meant for APC racks. Further, all these racks are having live servers running for 24x7 production systems. To arange for rack shifting or replacement requires a great deal of effort for seeking clearance and high cost will be incurred. Of course, one of the major concerns is 'what if a few servers just refuse to wake up after the shift?'. The space between the racks is about 3 floor boards or less. I would like to seek your expert advice on what other alternatives I have to improve the cooling efficiency for the server rooms. Thank you very much for your help and advice. Best regards, Kai Beng

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To improve the cooling effciency you must stop the hot and cold air from mixing. The only way to do this is by designing hot and cold aisle and putting blank plates in the unused space in your racks. This way the cold air is pulled through the servers by their internal fans. .

Rack shitfing is most likely your only hope to get hot and cold aisles. If you do not address this now it will only get worse. The expense of doing this move may be saved in your electric bill but for a true ROI you must do hot and cold aisles and move the cooling closer to the load. In some US states the government is giving rebates to companies who make their Data Centers more efficient.

If you have a sealed room (walls to the deck above) with a raised floor and ceiling . I would use the ceiling as a return plenum to your AC systems and put open returns in the ceiling of the hot aisles to move the hot air out. Both APC and Liebert make AC systems that can do this.

To answer your question better I would need to see a floor layout.

Michael Haley
Consulitng Engineer
NE Harris Assoc, Inc.

Even if you dont want to buy the new racks, you should prepare a plan for laying out the existing hardware in a hot/cold manner, and then use that as a master plan to work in during various outages and you will ultimately get there.
Regarding the fear of ”what if a few servers just refuse to wake up after the shift?”, you need to be ready for that. What if some server went down today due to a powerspike or got too hot or whatever? What are your plans for thaT?

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  • StevenG7
    There really isn't enough information provided in the original question to propose a solution -- for example: are you using underfloor cooling with a raised floor, or a slab floor? What problem are you trying to solve? -- hot-spots, uneven room temperatures, or just reducing energy costs? What type of power/thermal distribution do you have? (high-density racks, blades, low-density, etc.?) Hint: in some scenarios, hot & cold isles are of little value! Certainly, the goal is (as Michael stated) to keep hot & cold air from mixing, but in some environments you might not be able to achieve that. In that case, sometimes creating a turbulent airflow and mixing the air (to achieve uniform temps) is the best option. This is certainly not as efficient as a "properly designed" air distribution system but can often be achieved with no downtime and minimal cost investment. If you eliminate hot-spots and provide uniform air distribution, you can often raise the average temperature in the room and thereby reduce cooling costs. Without more information, I can't be more specific. Steven Gold Infrastructure Consultant SJG Consultants
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  • FacilityGuru
    I would have to add to Steven G's response in that there isnt enough information to really provide a 'hard-n-fast' answer, but there are things that do work physically to assist in this process. THere is a Covered-foam product called 'Gap-Hog' which works and I have used sheets of plexiglass cut to fit under/inbetween/on-top of cabinets as well as regular blanking panels in racks that dont have equipment in them. I hope this helps! Facility-Guru Austin, TX
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  • Bott
    I have the same situation as you. We ended up moving our production out into a third-party data center. We didn't have the people to manage HVAC, systems, network, and everything else. (Small business, highly reliant on IT infrastructure) We ended up with much lower costs this way. We also virtualized heavily and reduce our server counts significantly. Obviously you may not be able to do any of these (politically or financially), but they are alternatives.
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  • Batman47
    Install a Liebert cooling rack.
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