RE: DATACENTER: AC and colo sizing question.

[Nathan Stratton <nathan@robotics.net>]

Yes, but CMOS functions better at lower temps. In fact if you lower the
temp to -12^ C you can 2X the clock of any CMOS chip. :-) Now -120^ C may
be a little cold fo a datacenter, I think you will find that your hardware
lasts longer at 65F then it does at 73F.


><>
Nathan Stratton
nathan@robotics.net
http://www.robotics.net

On 16 Feb 2000, Sean Donelan wrote:

> On Mon, 14 February 2000, "Christopher E. Brown" wrote:
> > 
> > I would say 65F rather than 75F, with an absmax of 70F.
> 
> Most modern electronic equipment can operate in a "nominal"
> office environment.  Unfortunately, you rarely find this
> environment outside of textbooks.  There is also telco/NEBS
> equipment which can handle greater environmental extremes, and
> computer room equipment which can handle less environmental
> extremes.  But if you have one of the later, you usually know
> the specific requirements you have to meet.
> 
> You throw it all together, and what do you end up with?
> It seems like many people punt, and over-specify their
> requirements.  This is very energy ineffecient, and costs
> you a lot even in the short run.
> 
> I've found 72F (+/- 3F) will satisify nearly 100% of electronic
> equipment commonly found in computer rooms.  Even the most
> temperamental pieces of electronic equipment have a maximum
> recommended temperature no lower than 77F (25C).  Note: all
> measurements taken at the equipment air inlet, not at the CRAC.
> 
> The extremely few things which require even stricter environmental
> controls, tend to come with their own planning guide, dedicated
> chillers, and so forth.  The bench around a Cray supercomputer wasn't
> just for looks, it was functional.
> 
> > Whatever the size of the room good airflow is a must, hot and
> > cold pockets are a *very bad thing*.
> 
> You point out the most common problem in datacenters, poor airflow.
> People try to compensate by lowering the temperature, but this causes
> other problems such as humidity control and condensation.  Neither a
> steam bath nor a meat locker are good for electronic equipment.
> 
> > The equipment is designed to operate with a max intake air
> > temp of X with Y CFM flow.  You must maintain an input air temp well
> > below the devices rated max, and prevent obstructions to the airflow.
> > 
> > This means paying attention to where devices exaust to, and
> > keeping said exaust from the intake for other devices.
> 
> Yep, a rack is its own mini-climate.  The temperature can vary tens of
> degrees from the bottom to the top.  Injecting super-cooled air into
> the bottom, hoping it won't be heated too much by the time it reaches
> the top isn't the best method.  But rack design seems to be a lost
> art.  In the "old days" (i.e. 10 years ago) there were specialists at
> all the mini and mainframe companies which took great care planning
> cabinet layouts.  In today's world of Do-It-Yourself server assembly,
> the goal seems to be cram as many ascend maxes into a 84" rack as
> possible with no thought.
> 
> Patient: Doctor, Doctor, it hurts when I do this.
> Doctor: Don't do that.
> 
>