RE: dc servers

Here we run many -48VDC implementations.  While it does greatly simplify the
whole UPS issue, and reduce your overall cooling load significantly by
eliminating an AC-DC conversion step (and move much of your heat load to the
power room instead of the NOC) it has it's own challenges.  Instead of huge
UPS's you end up with huge chargers and battery banks, wiring is twice as
heavy and therefor twice as expensive, power supplies and PDU's are more
expensive for DC.  

If you have a number of racks of servers there is a lot to be said for going
DC, but without the opportunities afforded by scale I don't know if the ROI
is there.  

> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]] On Behalf Of John van 
> Oppen (list account)
> Sent: Friday, September 12, 2008 6:46 AM
> To: [email protected]
> Subject: RE: dc servers
> 
> Why not just go to -48v...  you can get servers with DC power 
> supplies for -48 volt as well as rectifiers which are either 
> single or three
> phase depending on the size.     All the big telecoms use 
> -48v DC plants
> due to the reliability you were looking for.
> 
> 
> 
> John van Oppen
> Spectrum Networks LLC
> 206.973.8302 (Direct)
> 206.973.8300 (main office)
> 
> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]]
> On Behalf Of jp
> Sent: Saturday, September 06, 2008 7:19 PM
> To: [email protected]
> Subject: Re: dc servers
> 
> On Sat, Sep 06, 2008 at 05:11:44PM -0500, Frank Bulk wrote:
> > Wow, that sounds like MacGyver.
> 
> No MacGyver would do it with ducttape, improvised leyden 
> jars, soldered with thermite, and it would power an AT&T PC 
> 6300. The biggest differences between myself and MacGyver are 
> that I've got firearms and newer computers.
> 
> > Why not get a server with two AC power supplies, and serve them off 
> > different UPSes?
> 
> I've got too many UPSs on racks as it is now. If I 
> centralized things with big redundant UPSs, I'd have to run 
> twice as much wiring in the datacenter and have twice as many 
> computer power supplies to manage.
> 
> > 
> > Frank
> > 
> > -----Original Message-----
> > From: [email protected]
> [mailto:[email protected]] On
> > Behalf Of jp
> > Sent: Friday, September 05, 2008 5:01 PM
> > To: [email protected]
> > Subject: dc servers
> > 
> > I've been thinking of better ways to provide uninteruptable 
> power, and 
> > 48vdc is proven nice but too expensive for commodity computing 
> > equipment and the wiring is more expensive than normal 
> utility wiring 
> > due to the lower voltages.
> >  
> > I've read that most autoranging switching power supplies as used in 
> > computers can run off DC.
> > 
> > I'm thinking I could run three-phase AC into a diode network to get 
> > full-wave-bridge-rectifier really smooth output with really 
> well phase 
> > balanced input. This would give me 120vdc.
> > 
> > I could wire in series a string of AGM UPS batteries that 
> would float
> at
> > 120vdc, then I could distribute power to the servers from 
> there. The 
> > capacity would only be limited by the basics such as the 
> diode current 
> > capacity, battery output current, breakers, and wiring used.
> > 
> > Punch some holes in my crazy plan if you are qualified. Has anyone
> used
> > such a system? This could handle a lot more load for less 
> money than 
> > most big line-interactive UPSs and would have no cut-over 
> delays like 
> > the 48v gear.
> > 
> > --
> > /* Jason Philbrook | Midcoast Internet Solutions - Wireless and DSL
> >             KB1IOJ | Broadband Internet Access, Dialup, and Hosting
> >   http://f64.nu/   |   for Midcoast Maine    
> http://www.midcoast.com/
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> > Eat sushi frequently. - Avi
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> > --
> > Eat sushi frequently. - Avi
> > [email protected] is the human contact address.
> > [email protected] is the list posting address.
> > See below URL for subscribe/unsubscribe and list options:
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> 
> --
> /*
> Jason Philbrook   |   Midcoast Internet Solutions - Wireless and DSL
>     KB1IOJ        |   Broadband Internet Access, Dialup, and Hosting 
>  http://f64.nu/   |   for Midcoast Maine    http://www.midcoast.com/
> */
> --
> Eat sushi frequently. - Avi
> [email protected] is the human contact address.
> [email protected] is the list posting address.
> See below URL for subscribe/unsubscribe and list options:
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> --
> Eat sushi frequently. - Avi
> [email protected] is the human contact address.
> [email protected] is the list posting address.
> See below URL for subscribe/unsubscribe and list options:
> http://inet-access.net/mailman/listinfo/list
>

-- 
Eat sushi frequently. - Avi
[email protected] is the human contact address.
[email protected] is the list posting address.
See below URL for subscribe/unsubscribe and list options:
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