Device power draw

[Dieselboy]

Is it normal for equipment with two or more power supplies, to be split across UPS power and dirty power? I'm concerned about power surge on the dirty power, risking breaking the equipment.

Is this a valid concern? I'll look into a surge protection thingy-majig, but wanted to query your brains here.

Changed the title to "device" power draw

[icecream-guy]

If your systems can support power in redundancy, then loosing one power supply should not affect the system. with smartnet, if a power supply fails, open a TAC case and a replacement will be shipped quickly. Shouldn't break the equipment, possibly if the system need both power supplies in combined mode to run the device, and one power supply failed causing a fault on the device..

Typically it's one power supply each connected to a different electrical circuits with being connected through a UPS to help filter dirty power,
the UPS can be skipped if one had "emergency" power through separate circuits and a jumbo UPS in the basement run by generator.

[Reggle]

I prefer the dual-UPS setup. I've seen the one-UPS-one-directly setup when people try to save costs in the design. Of course it's important what you're exactly trying to protect. I know a company that uses double UPS for the data center and the campus cores, but the campus access layer is single UPS for the help desk and even no UPS for some other departements.

Power surges don't tend to break more than the (swappable) switch power supplies as ristau said.

[Dieselboy]

Guys thanks very much for this info!

I would love dual UPS's.. I think I can ask for this at some stage in the future but for now I have the one UPS with extra batteries. We have smartnets, and I will keep them renewed. I hadnt thought that it's okay for the PSU to be fried, like that.

Regarding some units requiring dual PSU to operate normally, I was checking this up yesterday for the UCS 5108 chassis we have. It has 4 PSU's and they're all connected to the same UPS at the moment. I think this is a risk as the UPS can fail so the plan is to move some power to a dirty power for resilience. I was checking if this is possible or whether the chassis needs 2, 3 or 4 PSUs connected to run normally. I found out that I do need to make a config change, but it's fine to lose 2 PSU's or the UPS (Or dirty power) and one PSU from the working power supply. I also found out that the chassis has 4 x 2500W PSU's and we're currently using 500W! Even if all 4 servers within were running 100% load 24x7 then we would still only be using 2300W.

Thanks again, I'm glad I asked

[mmcgurty]

We do a UPS and then an APC AP7900 for normal NEMA 5-15 in places like a building IDF closet.  We do half the power supplies to the APC AP7900 on wall power only and the rest on an APC SmartUPS.  The reason for this is back in the day if the UPS battery died a lot of the UPS'es just quit working and that isn't good when both the primary and secondary power supplies are plugged into it.

[Dieselboy]

We do a UPS and then an APC AP7900 for normal NEMA 5-15 in places like a building IDF closet.  We do half the power supplies to the APC AP7900 on wall power only and the rest on an APC SmartUPS.  The reason for this is back in the day if the UPS battery died a lot of the UPS'es just quit working and that isn't good when both the primary and secondary power supplies are plugged into it.

Yep, this is one of the reasons I'm moving stuff around