UPS setup

shankshank
shankshank used Ask the Experts™
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Let's take Dell R710 servers, 6 of them.

Which setup would be best, let's assume a 5 min load time.

SOLUTION A:
2 x APC Smart UPS XL 3000
Each server has a power supply plugged into a UPS

SOLUTION B:
1 x APC Smart UPS XL 5000

SOLUTION C:
2 x APC Smart UPS XL 3000
3 servers connected 1 power supply to UPS1
3 servers connected 1 power supply to UPS2
2ndary power supplies of servers connected directly to wall outlet


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Solution A would be the best, a power supply for each, instead of one, because if that one goes down all of it goes down, if you have 2 you still have one of your servers connected.

Author

Commented:
But if 1 goes down, then they are all taking power from 2..

and if 1 goes down because its hardware failure, as opposed to a power outage, then the servers go down..

So wouldn't it be best to plug in the other power supply directly to the wall, or at least through a simple surge of some sort?

Author

Commented:
Also the Smart-UPS XL, I see a RT one, for $1000 more. what's the catch
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That is really low..

Author

Commented:
what is really low
The cost.
Commented:
As the configuration of the computers was not specified then;
Let us propose that you are using the 870W x 2 redundant power supplies in the 6 Dell R710 servers that you list. Ok, so 1 side of the dual power supply  x 6 servers x 870watts  is 5,220 watts per seond that the server stack is pulling per redundant power supplies. According to the APC spec page the APC Smart UPS XL 5000 is rated at, "Output Power Capacity 3600 Watts / 4500 VA ", not quite enough to feed the 6(six) units if the redundant power supplies are the 850 W units that I would personally would have put in to accomidate the max Up to 192GB in (18 DIMM slots): 16GB DDR3 1333MHz RAM and Up to 12TB2 via six x 3.5" 1TB2 hot-plug SAS or SATA hard drives that the machines can support. For all this you would need a lot of power. So  none of  the listed alternatives would suffice.

All the above points to the dual redundant power supplies in the 6 Dell R710 servers that you list being the smaller 570watt units. Ok, so 1 side of the dual power supply  x 6 servers x 570watts  is 3,420 watts per seond that the server stack is pulling per redundant power supplie. According to the APC spec page the APC Smart UPS XL 5000 is rated at, "Output Power Capacity 3600 Watts / 4500 VA ", just  enough to feed the 6(six) units on only 1 side of the dual redundant power supply. What about te other side? Solution C points to a kind of an answer but I personally would NEVER connect any power supply for any server directly to the AC mains, EVER. Now you can this and hope for the best. I would just get two of the Smart UPS XL 5000's, connect all of  the side 1 redundant power supplies to the left  XL 5000 and all of  the side 2 redundant power supplies to the right  XL 5000. Then I would connect all of the networking hubs, switches, routers and other small loads to a Smart UPS XL 3000.

Contact an electrican or staff electrican to verify that you have enough AC current load capacity for the UPS's and computing loads.  Per APC the load would be 3,420w for the computers per redundant power supply and add 1,000 watts for the internal operaing and recharging circuitry giving you a per
UPS load of 4,420 watts at 208 volts. This yields a per UPS current of 21.25 amps minumum, the NEC handbook indicates that a supply in excess of 125% of the full load amps be avaliable. So, 21.25 x 1.25 is 26.56 amps. This is a normal load using a dedicated 230 amp supply from the power panel to a NEMA L6-30R wall outlet. You will need two of these for the two UPS's.

Information for the Dell machines was gathered from:
http://www.dell.com/us/en/enterprise/servers/server-poweredge-r710/pd.aspx?refid=server-poweredge-r710&cs=555&s=biz

Information for the APC machines was gathered from:
http://www.apcc.com/resource/include/techspec_index.cfm?base_sku=SU5000R5XLTXFMR

Information for the electrical work from the National Electrical Code® Softbound 2005 Online Access

If there are further questions please post here and we will answer them.

I hope that this helps. curtisla

Author

Commented:
NIce answer. thanks

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