Going to need to write up a site preparation sheet …

… that covers some basic things. Like cooling, power, IPMI, …
We’ve seen a common thread throughout a number of data centers recently, where we’ve placed a machine. Occasionally, the airflow will be too low or, following the fads as of late, too warm, to be effective at cooling a high performance machine.
More to the point, its great when your density per rack U is not that high to have warmer air or less air flow going. Web servers don’t generally run terribly hot.
But start pushing GB/s through memories, through RAIDs, through networking cards … yeah, you start getting hot.
Now add to this the nice high inlet temperatures …
Less dense machines don’t care so much. More dense machines … they care.
I can’t wait till people start putting GPU clusters into these rooms with 74+ degree ambients, and limited airflow.
Ugh. High inlet temperatures coupled with low flow … just say no.

6 thoughts on “Going to need to write up a site preparation sheet …”

  1. (Oh Eris, cookie error again. And I did *not* save my posting! Dang… Again, from scratch.)
    We had this site documentation framework in my old company and I have to admit that all the documentation I’m making up today is somehow aligned to this. Though, in those day, we didn’t have to deal with those heat dissipation figures like today. I got to say though that our Primepower 1500 spit out something like 11 kW/m^2, which was pretty awful for a datacenter back in 2006. And still probably is.
    Nether the less, our engineering requirements were only a simple spreadsheet, summing up all the Watts and BTU/h – we handed this over to the hoster and simply asked him for “compliance”. That wouldn’t work with dense datacenters like we have now, but still it’s the only thing I could do.
    Unless someone comes up with a nifty spreadsheet which actually calculates something like “airflow intake m^3/h” and “heat dissipation in BTU/h” and makes up some clever calculation about the actual heat at the fan’s rear end. But on the other hand, the HVAC guys are usually lucky when I tell em that I spit out such and such Watts.
    If you happen to make such a cool spreadsheet, please share. I’m willing to trade in some clever templates for site surves reports, engineering requirements frameworks and other geeky stuff.
    Cheers, Alex.

  2. @Alex:
    We might have to do this (funky spreadsheet). Its getting nuts dealing with some of the fads I see in data centers.

  3. @Chris
    Heh … we worked with a partner on a design that came very close to 30kW/rack 🙂
    High density demands better cooling. More smaller faster fans don’t move air as quickly as larger slower fans.
    I do think we are getting quite close to the limits of air-cooled systems for density purposes. Oil-baths or DI water are interesting solutions, though the potential failure modes are … er … bad. We need some new solutions. Localized chassis based liquid cooling with efficient heat exchangers for waste heat rejection/transport.

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