[dc-ops] General opinions about AC cooling..

[Kaj Niemi]

Hi,


This is IMHO a 'it depends' kind of thing ;-) It might be good to know what
size of a facility you're looking at (100 m2, 1000 m2, 5000 m2).

Personally I've built DCs underground with inline cooling every N
cabinets/row and did not use raised flooring. There are a few things to
remember, namely when adding additional rows and inline units one needs to
carefully balance the network feeding the inlines both for volume and
pressure. Inline gets really expensive really fast, too, if you're not
careful. One needs to take in account (if you're into PUE gaming) that each
inline unit also consumes electricity.

A busway/busbar system gives you more flexibility on where to put your power
per row instead of using dedicated cabling direct from PDU. At the same time
if the busbar fails or PDU breaker trips where the busbar is connected it'll
take a quite large hit to your power distribution within the room.

I think your roof will be very heavily utilized if you place copper, fiber
and busway up there. Planning that real estate must be done with some
serious thought on what's going where. If you're pre-cabling all racks at
day 1 it won't be a problem when properly planning it but as most DCs are
built in phases or ad hoc after initial install it might get tricky to fit
everything up there, add/remove things, etc. It might also work if you put
the baskets/rails for copper/fiber directly above the racks and the busbars
directly above the rear aisles (usually hot) aisles. If doing hot/cold
containment again one must take in account serviceability to all components
+ doors (usually the sliding kind). Another option would be to place
fiber/copper above the cabinets and the busway/busbar below the raised
floor.

Some disk vendors (EMC, NetApp, HDS?) seem to require that their racks get
air from below which, if you have some, makes raised flooring kind of
mandatory.

As for Halon, at least in Europe it's been banned for a while. Perhaps you
meant Halotron (which is a clean agent)? When any total flooding fire
suppression system is about to get released all air vents should
automatically close to make the room as airtight as possible.



HTH


Kaj

From:  Eric Tykwinski <eric-list at truenet.com>
Date:  Mon, 28 Nov 2011 11:07:53 -0800
To:  "dc-ops at puck.nether.net" <dc-ops at puck.nether.net>
Subject:  [dc-ops] General opinions about AC cooling..

What do you guys think about ditching crac units and raised flooring?
 
We¹re still in the planning stages of building out a new Data Center.
Since we are going for a Busway system for power, the only need for raised
flooring would be AC units.
We talked about doing in row AC units, but are now leaning more to redundant
commercial units, like Trane 30¹s.
Mainly the reason being outside air economizers, and other options that can
be built in from the factory.
I would guess as long as the filtration is good, there shouldn¹t be any
issues with the halon system or particles.
 
I don¹t see any issues with this setup, but would like to hear opinions from
both sides if possible.
 
Sincerely,
 
Eric Tykwinski
TrueNet, Inc.
P: 610-429-8300
F: 610-429-3222
 


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