[Beowulf] bring back 2012?

Stu Midgley sdm900 at gmail.com
Sat Aug 20 07:03:29 PDT 2016

> I don't need to try to do that, because that's the job of the engineers at
> Asetek, CoolIT and their OEM partners. I've looked at their solutions every
> year they've been as SC, and the packaging is quite neat, and included heat
> exchangers for the RAM to keep it cool, too.  I sure as hell wouldn't want
> to engineer and build the system myself, but I'm sure glad there are others
> doing it, and I have a lot of confidence in their work.

Spoken like someone who doesn't have to take responsibility or pay for
their solution.  I work in the private sector and have to satisfy
customers.  If a solution doesn't work, or has continual problems or is
delivered late, I have to answer for that and our company suffers.

> Now my criticisms, which apply to mineral oil immersive cooling only:
> * The stuff is messy. I can't imagine removing components from a server
> without them slipping out of my hands. I can't even imagine getting one
> from the tank to a workbench without getting oil everywhere. I'm sure you
> can clean it off with a lot of electronic parts cleaner, but how good for
> the environment is that?  I see this stuff gaining more market share when
> we get to 'disposable' servers with ARM-based SoCs, so cleanup isn't even
> an issue.

I work with the stuff as do our local SGI engineers and it isn't that big a

> * Liquids are dense! Immersive cooling in mineral oil adds a lot to the
> load of the data centers raised floor. Yes the tanks are about the size of
> a rack flipped on it's side, but even the densest servers are still mostly
> air by volume. I imagine many data centers would need to upgrade their
> floors before going to this type of cooling.

Wrong.  Prior to immersive cooling, we were running SGI chilled water
racks.  A 40RU tank with nodes comes in at about 1600kg's... an SGI chilled
water rack with nodes comes in at about 1400kg's.  The SGI rack has
1400kg's in less than 1msq whereas a tank is 1600kg's in just over msq...
it is actually better for your floor.

> * Since the "racks" are on their sides an only go up about 3 - 3.5 feet,
> it's not a very efficient use of space. We often talk about data center
> space in square footage, but it's *volume* that really matters, and I don't
> think mineral oil cooling is very space efficient.

Wrong.  If you take a rack and the clearances of the back and front
required to service nodes (400mm at the back 900mm at the front), you take
about 2sqm per rack... which is less than our tanks currently take.  We can
get MORE density with an immersive solution than with racks.

> * What if one of those tanks leaks or a pipe bursts? I'd rather clean up
> water or Novec. Yes, there are electrical dangers when that happens with
> water, but that's what circuit breakers and such (GFCI, AFCI, etc.) are
> for.

Water is actually worse than these fluids.  If you get a leak, you use a
wet-vacuum and suck it up and put it back into a tank.  You don't have to
worry about any electrical components or other mechanical stuff.  The
fluids are easy to clean up, wipe down and get on with life.

> * What happens when you decommission hardware that's covered in mineral
> oil? How do you clean it up? Will a recycling center take electronics
> covered in mineral oil.

When you decommission nodes, you throw them out like you do with all old
hardware.  The fluids are non-toxic, biodegradable, have a clean MSDS and
nodes/components can be disposed of clean or oily.

Dr Stuart Midgley
sdm900 at sdm900.com
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