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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