server room - rack spacing - AC

Tue Aug 23 16:00:34 PDT 2005

Alvin Oga wrote:
> hi ya 
> 
> thought i'd post here again ... ( for fun )
> 
> - we're looking at building out a server room with 
>   42U cabinets and telco racks
> 
> - what is the minimum spacing in front of the racks
>   and cabinets to allow the 1Us to be pulled out ??

Typically 36 inches.  I have seem some Sun gear (ie 450) that will take 
every inch of that to put it in a rack.

> - their "server room expert" ( aka interior designer at the
>   real estate outfit ) wants to use 30" or 39" in front of the
>   cabinet, it was fun to google their names to check
>   their backgrounds

Demand at least 36 inches.

> - some of the dell box is 29" deep plus additional say 6-12"
>   of cables and gap so you can hook up to the box that 
>   is extended out of the cabinet 
> 
> 	- at 39", you cannot stand in front of the cabinet
> 	and racking things from the sides is too much work
> 	to hold up 30lb or 100lb rackmounts while you align
> 	it into the slides

Bingo!  Although, I find rack rails are more trouble than they are 
worth.  Also, just try to get all vendors to agree on the spacing 
between the front and back rack supports. :-)

> - cabinets are 40" or 50" deep ... which means whatever
>   goes inside can be up to 40" long too and will extend
>   out of the cabinet by about 40" + clearances for cables
>   and adjustments for different types of slides

When you mean 40 to 50 inches deep, then you are not counting the 
outside dimensions?  If so, take at least 4 to 6 inches off of that 
depth for how deep the gear can be.  Rack rails will be recessed in to 
accomidate handles, buttons and switches in the front.

> - i'm hoping there's some eia/osha footprint standards

Depends on the rack you order.

> - we're using 2x 220VAC per rack ... but that too is being
>   cut down ...
> 
> - we've calculated by counting AC outlets ( P = iv )
>   or counting the "power supply wattage"  and came up
>   with about 50KW of power of existing systems
> 
> - AC tonage:  ( rounded answers )
> 
>   BTU/hr = (((I * V )*0.8)/1000) * 3413  ===>> 136,000 BTU/hr
> 
>   AC tons = ( BTU/hr ) / 12000 =============>> 10 Ton AC
> 
> 	and that too is being downgraded to a standard
> 	4-ton AC ... 

I have a spreadsheet I can send you that you can crank in square 
footage, power etc. and get a cost per rack and A/C needs if you want. 
We use it for planning our colo deployments at UnitedLayer.

Tim