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Re: data center loading (was:Re: rack power question)

  • From: Robert Boyle
  • Date: Wed Mar 26 11:29:17 2008

At 10:15 AM 3/26/2008, Lamar Owen wrote: 
One thing I haven't seen discussed, though, is the other big issue with
high-density equipment, and that is weight.

Those raised floors have a weight limit.  In our case, our floors, built out
in the early 90's, have a 1500 lb per square inch point load rating, and
7,000 pound per pedestal max weight.  The static load rating of 300 pounds
per square foot on top of the point load rating doesn't sound too great, but
it's ok; we just have to be careful.  Our floors are concrete-in-steel, on 24
inch pedestals, with stringers.

I don't know about others, but we don't use raised floors. If you look at the airflow required and how high your raised floor actually has to be (5-6 ft) in our case, it simply doesn't make sense. We use doors at the ends of aisles, blanking panels, and a lexan cover over all aisles. We sequester all air and force the air to flow through the equipment. This typically cuts energy used for cooling roughly by 30-45% We have seen dual 20 ton Lieberts used for a double row (typically 20-22 racks per row) actually cycle on and off once air is no longer allowed to mix. We typically will also use two Challenger 3000 5 ton units in the middle of the row for a total of 50 tons of cooling and about 150KW of electrical use for 35-40 cabinets. That is a mix of some cabinets with fewer servers and some with high density 10 slot dual quad core blade chassis units. We also like to build our datacenters on 8-12" slabs at or slightly above ground level so we don't really need to worry about weight loads either. Not possible if you are on the 20th floor of headquarters, but something to consider when talking about greenfield datacenter development.

-Robert



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