Hot computers take a dip
Sometimes you find heat in unexpected places.
once trying to to get my job done as quickly as possible, wiping the
sweat off my brow as heat poured mercilessly across me. Perspiration was
building on my hands and I had to keep wiping them across my shirt to
dry them off. But I wasn’t toiling in the hot sun. I was indoors, trying
to rewire a network connection inside an overly heated server room.
For a time, the heating problems of data centers and server rooms
seemed to diminish. Dual- and quad-core processors took on the burden
of several machines at the same time, reducing the number of
heat-producing boxes. The GCN Lab is in the process of turning most of
our test bed into virtual machines hosted by just two servers, which
will greatly help our heat problems.
In large data centers,
something else happened. First, the number of machines shrunk, but then
they grew again as centers expanded their capacity with the new
machines. Only this time the multicore high-density machines produced so
much more heat that air cooling alone could hardly keep up.
about this: A standard rack with 30 kilowatts of power going into
modern systems produces as much heat as turning the stove in your home
to broil and then opening the door. That’s hot, and data centers and
server rooms are filled with these racks.
In Texas, where it gets ungodly hot anyway, the Austin Advanced Computing Center is
experimenting with immersing systems into liquid to keep them running
cool. Instead of water, they use a nonconductive mineral oil, remove the
fans from systems and seal the hard drives to keep liquid from leaking
in. That’s a few extra steps to keep things cool, but the servers run at
a constant 115 degrees Fahrenheit now, which is about what you could
get when blasting cool air into the enclosure anyway, the water being
more efficient as a cooling medium.
I would not give up on air-cooling just yet. In the September issue
of GCN, we review a portable cooling unit from Tripp Lite called the
SRCOOL12k that uses a unique direction tube to funnel cool air directly
into a server rack. In our testing in the lab (we have not completed
our VMware project yet), it really cooled our systems down without
having to modify them in any way.
Even with positive results on the Tripp Lite unit, air cooling may be
a stopgap method at best. But water cooling has a lot of problems, too.
We experimented with water-cooling individual systems with the Domino ALC cooler. It
got a positive review, but there were quite a few problems later on.
The biggest difficulty is that systems are not designed to take a
water-cooled system, which is inherently bulky. We ended up stuffing the
ALC into a test system, and it was so cramped that it eventually
leaked. Because it was filled with distilled, non-conductive pure water,
it did not complete any circuits and damage the unit, but it’s never
good to find water leaking out of your computer when you arrive in the
morning. Even in the Austin facility, computers have to be modified
before they can safely work underwater.
It’s clear that our appetite for extra power is resulting in too much
heat being generated, and that will eventually cause more than just an
occasional problem. I don’t think that data centers are going to be
anytime soon, though images of IT guys in diving suits going into the
deep blue to bring a new server online is intriguing. Perhaps we can
train dolphins to fix servers for us.