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Trying to determine if my power infrastructure can accomadate a new blade enclosure

Posted on 2009-04-29
Medium Priority
Last Modified: 2013-12-11
We have a Symmetra PX 20kW UPS in our data center. I am trying to determine whether or not it can provide the required power for a HP BladeSystem c7000 Enclosure. Currently the UPS shows a load of 63%. Please let me know if you need more information. I'm not sure how to calculate this ? Thanks in advance.
Question by:chaz21

Expert Comment

ID: 24267971
Offhand, I would say no if you want a run time of more than a few minutes at peaks.
It really depends on how many blades, and which type, and the power supply configuration.

What is the input voltage and phase of the UPS?

Your currently at 63%, which should be around 12.5kW. If you have a full blade chassis, you could possibly peak at ad additional 14.4kW if you have high temp's, high cpu utilization, high i/o etc..

If you plan on growing the blade center incrementally, and you start out small, you will probably be fine for a while.


Author Comment

ID: 24271150
the input voltage is 208V 3-Phase

from there we deliver power to the racks using switched rack pdus @ 120V single-phase

the blade enclosure we are looking at is the HP BL c7000 CTO.

the power supply type listed on hp's website is a 2400W high efficiency power supply. the enclosure would use 6 power supplies (single phase IEC-320 C20 @  

our goal is to consolidate about 25 physical servers to the blade enclosure using vmware. we would have to power the blade enclosure and the servers that will be replaced during the p2v (physical to virtual) conversion.

my thinking is that once we have all of the old hardware converted to virtual running on the blade we should be ok ?

thanks for the insight, really appreciate it.

Expert Comment

ID: 24273769
As long as you decommission servers as you bring up blades and keep your power balanced, you should be good, just make sure monitor your UPS load, and keep your essential servers on the UPS. If your budget allows, you might want to expand that UPS to 40kW.
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LVL 17

Expert Comment

ID: 24274131
jbristle has a good suggestion but it sounds like you want all of it running at the same time. Would it be at all possible to borrow or rent an additional UPS and power from somewhere until you can decomission the old servers?

Author Comment

ID: 24274245
our frame is actually maxed out at 20kW, their is no room for expansion so unfortunately that's not an option. there's a total of 3 power modules @ 10kW each with two being active and one acting as spare.

we do have some old APC equipment lying around, however, source power comes into the data center straight to the symmetra. i'm not sure how we could utilize the old equipment without source power ?

jbristle,  can you explain how you came up with 14.4kW for the blade enclosure ? it would be greatly appreciated. thanks again for all this great information. to a novice data center administrator its quite helpful!

Accepted Solution

jbristle earned 2000 total points
ID: 24274399
I went by the spec's sheet for the c7000 chassis. 6x power supplies, peak at 2400W each (worst possible case).
You should never see a load near that unless you have an A/C failure, or you just have a huge load on the blades, or you go crazy with storage blades. Depending on which blade config's you use, you will probably not utilize all 6 psu's. Ideally you would configure them in a redundant mode.

But, even assuming half peak load (50% of 14.4kW), you will still be at 7.2kW, which will more than put you over your threshold for a 20kW UPS. Remember, you do not want to run your UPS 100% - ideally around 80% maximum. Besides having a couple of minutes run time, you risk popping breakers if you have a power spike from several server spinning up at once.

According to APC, all of the Symmetra PX UPS are scalable. This is of course, assuming that your model matches their current spec sheets. It may also not make sense to upgrade the UPS vs. adding an additional unit.


You may want to talk to your building maintenance or electrician, your breaker panel may not be maxed out.

Expert Comment

ID: 24274433
This is a great section of the APC site for gathering this kind of information.  There are selectors for multiple aspects of your business.  You can usually build these to very closely fit your specific situation.



Author Comment

ID: 24274694
this is actually our exact model:


i had to call apc to get that link b/c i couldn't find it anywhere on there website either. so we are indeed maxed out.  there is an option to run all 3 modules at once so 30 kW but then we wouldn't have redundancy which to me wouldn't make a whole lot of sense.

i doubt that we would want to add an additional unit as the investment for this project (blade enclosure, vmware licenses, and shared storage) is already pretty high up there.

based on these numbers:
20kW max capacity
12.5kW already being used
and the blade enclosure requiring at least 7.2kW

i don't see how our current infrastructure would be able to handle the load.  would you guys agree ??


Expert Comment

ID: 24274827
You could give it a bump to 30kW for a short period while migrating the servers. But if you have any concern for redundancy, I would not.

Considering the cost of the new blade center, I would try to get funding for a new UPS also and have a talk with your electrician about bringing in some more circuits.


Author Closing Comment

ID: 31576152
awesome insight and advice very much appreciated !!

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