The heating ventilation and air conditioning as an element of design
resilience. Research out of Toronto University illuminated that the
world's data centers are estimated to consume power equivalent to about
17 1000‑megawatt power plants, equaling more than 1% of the total
world's electricity consumption.
Now, that was a study that was done some 4 years ago,
so it wouldn't be a shock to discover that that
footprint has become heavier and heavier.
Most of the cost of the data center is actually for cooling.
That same study showed that the yearly cost of running the
cooling infrastructure for a typical data center can reach
anywhere from $4‑$18 million.
Google states that their data centers use much less
energy than the typical data center.
They raise their temperature to 80 degrees Fahrenheit, use outside air for
cooling, and build custom servers, and they have detailed performance data to
help move the entire industry forward, showing that they get better efficacy
from running at those temperatures anyway. The standard recommendation from
ASHRAE, American Society of Heating, Refrigeration and Air‑Conditioning
Engineers issued its first thermal guide for data centers way back in 2004. The
original ASHRAE temperatures recommended this range of 18‑27 degrees Celsius,
roughly translates to 68‑77 degrees Fahrenheit; also, a 5‑15 degrees Celsius dew
point.
Now, the dew point, if it is too low,
obviously, can induce an environment full of static electricity, and if
it's too high, can promote corrosion. Sixty percent should be the relative
humidity that is the larger measure of moisture.
There are two types of cooling, latent cooling, which is the ability for
the air‑conditioning system to remove moisture, and sensible cooling,
which is the ability of the air‑conditioning system to remove heat that
can be measured by a thermometer.
Those are the two types of cooling that take place.
Imagine a very humid place where you live and a very dry, hot place
where you live. Both of those would need a type of cooling to bring
the environment down so that it is livable. Inside the data center,
imagine that you had a bird's eye view and you're above the server
racks looking down.
Imagine then that you are arranging your servers in rows. So here we have a row
of three servers. F stands for front, B stands for back. The next row of
servers, we would actually put the back of those racks so that they are
back‑to‑back with the rack before, and therefore, the front of that second rack
with the third rack's front, and so on.
Now, this would allow us to have server inlet temperatures,
server outlet temperatures, in a more controlled fashion.
Imagine if we actually created the environment so that this
environment said that I'm going to make it so that I contain all the
hot air. Containing all the hot air by means of some type of
structure to prevent the hot air from leaving that aisle would be
what's called hot aisle containment.
Now imagine how the rest of the data center would feel.
It would most likely feel pretty cool.
But if you did something called cold aisle containment,
where you now contained the air from flowing freely in the
front‑to‑front configuration,
then the rest of the data center may actually feel inhospitable to humans.
It would really depend on what is it that you're
trying to derive from the environment.
What efficiencies are you bringing about? As stated before, many of
the major cloud service providers have actually moved beyond what
they would consider to be rudimentary,
but these are what the standards have been for a number of years.
Next, let's get into design resilience from an availability class perspective.