Rasberry pi - high density

Mon May 11 21:36:11 UTC 2015

>>> Pi dimensions:
>>>
>>> 3.37 l (5 front to back)
>>> 2.21 w (6 wide)
>>> 0.83 h
>>> 25 per U (rounding down for Ethernet cable space etc) = 825 pi

You butt up against major power/heat issues here in a single rack, not
that it's impossible.  From what I could find the rPi2 requires .5A
min.  The few SSD specs that I could find required something like .8 -
1.6A.  Assuming that part of .5A is for driving a SSD, 1A/pi would be
an optimistic requirement.  So 825-1600 amp in a single rack.  It's
not crazy to throw 120AMP in a rack for higher density but you would
need room to put a PDU ever 2 u or so if you were running a 30amp
circus.

That's before switching infrastructure. You'll also need airflow since
that's not built into the pi.  I've seen guys do this with mac minis
and they end up needing to push everything back in the rack 4 inches
to put 3 or 4 fans with 19in blades on the front door to make the
airflow data center ready.

So to start, you'd probably need to take a row out of the front of the
rack for fans and a row out of the back for power.

Cooling isn't really an issue since you can cool anything that you can
blow air on[1]. At 825 rpi @ 1Amp each, you'd get about 3000 btu/h
(double for the higher power estimate).  You'd need need 3-6 tons of
avalible cooling capacity without redundancy.

I don't know how to do the math for the 'vat of oil scenario'.  It's
not something I've ever wanted to work with.

In the end, I think you end up putting way too much money
(power/cooling) into the redundant green board around the CPU.

>> This feels like it should be a Friday thread. :)

Maybe I'm having a read only may 10-17.

1. Please don't list the things that can't be cooled by blowing air.

-- 

Pete