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Hot Aisle Or Cold Aisle For Containment?
1sockchuck writes "Separating the hot and cold air in a data center is one of the keys to improving energy efficiency. But containment systems don't have to be fancy or expensive, as Google showed in a presentation Thursday, which discussed the use of clear vinyl curtains in isolating hot and cold aisles. Containment systems have been in use at least since 2004, but there's an ongoing debate about whether it is best to contain the hot aisle or cold aisle. Leading vendors are split as well, as APC advances hot aisle containment while Emerson/Liebert champions a cold aisle approach. What say Slashdot readers? Do you use containment in your data center? If so, do you contain the hot aisle or cold aisle?"
If we were to retro-fit it at work, I'd say cold aisle. To do so would mean curtains at the end of the aisles, as the under-floor vent grids are in front of the racks. The CRACs are at the end of the room sucking in air through the top, so it'd be cool air pumped up through the floor, into a cold-only zone, sucked through the racks, blown out the back into the rest of the room where it just swirls about until it's pulled into the CRACs again. I reckon it could be done cheaply and quickly. Do do it with the hot aisles would require more containment to get the air back to the CRACs. I think it'd be a case of which air flow it fits best.
Maybe I'm missing something obvious, but the answer shouldn't be complex. Base the decision to contain either hot or cold aisles on the differences to ambient temperature. If (HotT - AmbientT) > (AmbientT - ColdT), then contain the hot aisles. If it's the other way around, contain the cold aisles. This minimizes the entropy loss due to temperature mixing in the data center, I believe. Just my 2 cents.
sigfault (core dumped)
The best solution is going to based on the average ambient temperature of your location. If you're in a hot environment, why contain the cold if you need additional A/C in the datacenter for employees? Reduce costs by using the same equipment to cool both. If you're in a cold region, then let the heat also warm the datacenter. If you're in an ideal temperature environment, then you don't have much to worry about beside good air flow.
I think containing the hot isle is probably the best way to go as well.
* When I'm working in a datacenter I'd rather be walking around in the cold isle (~70-80F in a modern datacenter) than the hot isle (100-120F if properly contained)
* Containing the hot isle and to a small space and using the rest of the air and space around the rack (up to the ceiling, walking isles, etc) allows more volume of cool air to be a buffer in case of low/failed cooling capacity.
I mean it worked for the McDonald's McDLT back in the 80's...
'He who has to break a thing to find out what it is, has left the path of wisdom.' -- Gandalf to Saruman
You forgot Iceland...
Yeah well, they're having a little trouble with containment right now themselves. And it appears geothermal isn't as clean as it was made out to be.
For justice, we must go to Don Corleone
Depending on how your facility is ducted, it might not cost much to try both options and measure the results.
Call me naive, but... Why not do both at once?
Cold air goes in from the bottom (or one side), through the rack, and hot air goes out the top (or the other side). I realize that companies don't really care about such minutiae, but that would allow the mere humans that occasionally need to service all those expensive racks to experience a temperature other than 40F or 120F.
Or, hey, how about just cooling the damned things with intelligently ducted outside air and cutting the electric bill by a third?