Mailinglist Archive: opensuse (3506 mails)

[Sandy Drobic <suse-linux-e@xxxxxxxxxxxxxxxxxxxxxxx>]

Roger Oberholtzer wrote:
> On Thu, 2006-09-21 at 17:02 +0200, Sandy Drobic wrote:
>
> > I heard the same screams in our company from my boss when the electrician 
> > told him our ups was underpowered (he assumed 400W each server). We now 
> > have a few servers more in the rack and the ups load is still safe at 
> > about 57%.
>
> Is it a non-switching UPS? Meaning that the equipment runs off the
> batteries all the time? If so, your UPS will last longer if the load is
> more than 57%. Otherwise, the batteries lose their charge capacity and
> will last a shorter time when power fails. We use UPS in road vehicles
> and have found this to be true. Our UPS suppliers have all said the same
> thing. An over-dimensioned UPS' batteries do not last as long. Same
> thing with petrol power generators. They last longer if the current
> taken is closer to their rated power capacity.

No, it's a switching UPS. Though talking about overdimensioned UPSs, a 
year ago, I had to buy a new one, because the old one broke down (guaranty 
had just run out), and APC told me they could only offer a trade-in if I 
took the next bigger version. Unfortunately, even the old one (8000VA) had 
a max load of 20%, so I felt a bit ridiculed by that offer.
I went and bought a new one (5000VA) for half the offered trade-in price 
which came equipped with a network monitoring card. Now I can use it to 
measure the temperature in the server room and scream for help if the air 
conditioning in the server room breaks down.

Here at home I use a switching 500W (750VA) UPS when short power outages 
became too frequent for my comfort.

Sandy
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