[c-nsp] rack power question

[Bill Wichers]

We've seen some customers order 2 x 120 volt, 30 amp power circuits
which is about 5.8kW, and it's not uncommon. With the new blade server
people coming in we see 208 volt, 30 amp circuits being ordered and
those are approx 5kW each and it's not uncommon to have people order
multiple circuits since you can usually fit 3+ blade chassis in a single
42U rack. We typically recommend to our customers that they keep their
total power consumption under 6kW to avoid their rack overheating, but
if the rack is completely full and you run hot isle / cold isle like we
do it is possible to exceed 6kW of power consumption in one rack and not
have overheating issues with the equipment.

 

We typically run our network stuff on DC power, and we have lots lower
power density there. The biggest problem we see with network stuff is
that so much of the devices run sideways air flow (not "in the front,
out the back", so we have to do funny air baffle setups to keep the hot
air from blowing into the intake of the next rack in the row.

 

   -Bill

 

> -----Original Message-----

> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp- 

> bounces at puck.nether.net] On Behalf Of Tim Durack

> Sent: Saturday, March 22, 2008 10:28 PM

> To: Patrick Giagnocavo; cisco-nsp

> Subject: Re: [c-nsp] rack power question

> 

> For a 6509-V-E with 2xVS-S720-10G-3CXLs and 7xWS-X6708-10G-3CXL.Cisco 

> Power Calculator shows:

> 

> 107.76 Amps     4525.92 Watts     18183.55 BTU/Hr

> 

>  At 21u you could squeeze two in a rack, for 9K (we aren't planning on


> doing that though.)

> 

> On the server side something like an HP C Class Blade Chassis with 16 

> blades can hit 3K when the fans rev up.

> At 10u you could squeeze 4 in a rack, but cooling is going to be an 

> issue. With enclosed ducted racks, we currently have plans to put 3 in


> a rack for a total of 9K.

> 

> So yes we could require >6K.

> 

> Tim:>

> 

> On Sat, Mar 22, 2008 at 10:02 PM, Patrick Giagnocavo 

> <patrick at zill.net>

> wrote:

> >

> >  Hopefully this classifies as on-topic...

> >

> >  I am discussing with some investors the possible setup of new

> datacenter

> >  space.

> >

> >  Obviously we want to be able to fill a rack, and in order to do so,


> > we  need to provide enough power to each rack.

> >

> >  Right now we are in spreadsheet mode evaluating different
scenarios.

> >

> >  Are there cases where more than 6000W per rack would be needed?

> >

> >  (We are not worried about cooling due to the special circumstances 

> > of  the space.)

> >

> >  Would someone pay extra for > 7KW in a rack?  What would be the 

> > maximum  you could ever see yourself needing in order to power all
42U ?

> >

> >  Cordially

> >

> >  Patrick Giagnocavo

> >  patrick at zill.net

> >

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