Some UPS calculations

17 Nov 2005 It's been a while since I've received any solutions for Fun University and I fear it might be getting less interesting to the participants. I've been thinking on porting the FU site to drupal to make it more interactive and in fact I've already created a site for it and everything. Now I just need to migrate and that seems to be the largest problem. I need to find out how I can create my own type of content (challenge and solution) and then I need to make such a type. Then I need some test users to see if everything works ok and after that, I need to port the entire previous site to drupal.

Also, a better PullThePlug stylesheet/theme for drupal would be a good thing, as the current one has some problems with foreground/background having the same color etc.

Furthermore, I decided to buy a UPS for the Ekonomika server a while ago and would have wanted to keep the entire path to the uplink powered up through the UPS in case power went down (again) in the ULYSSIS serverroom (where this server is located). The UPS I had in mind is the MGE Ellips ASR 1500 USBS which can provide 900 Watts (6.5A Max and the batteries are 7Ah, which means it can give 7A for an hour. 900 Watts is about 3.75A at 240V...), has a 3 year warranty and costs 260 Euro. I got green light from Ekonomika to implement my plan and buy the UPS, but they ask that if ULYSSIS is going to use the UPS aswell (to connect firewall and all switches switches in between the Ekonomika server and the internet uplink) that ULYSSIS would contribute a small fee.

The plan was sent to ULYSSIS, who would have a definitive answer after the next meeting. The answer is something like this: "We decided that the benefits don't weigh up against the cost. A switch of that price category [I mentioned 260 Euro] could keep the Ekonomika server + firewall and switches up for only about 10 to 15 minutes. That doesn't seem like enough to be useful to ULYSSIS."

This only shows how good the meetings at ULYSSIS are :) Everyone has a say even if they know nothing of the subjectmatter and noone seems to do any research.
"260 Euro? Hey that's not alot! It's probably not good enough then, let's ditch it"

According to my calculations, there is a total of 2 servers (Ekonomika and the firewall) and 3 switches (a small one of about 15W and 2 big ones of about 50? Watt?) to be powered by the UPS.

Let's ASSUME that everything is running at peak energy usage. A server has a 300W power supply (which is of course a maximum).
2 servers (300W*2) + 1 small switch (15W) + 2 bigger switches (50W*2) = 715W.
Well within what the UPS above can deliver.
715W at 240V is 2.98A. Let's call it 3A :)
The batteries have a capacity of 7Ah, which means at 3A they last for 2.5 hours. And that's a minimum! The servers don't swallow 300W.

Just to see which UPS they has in mind, let's do the reverse math.
10 to 15 minutes of power... Let's take 15 minutes. 3A for 15 minutes is 0.75Ah.

What the hell kind of UPS is that ? We're living in the 21st century people