UPS For Server Cupboard

[dhicks]

Most hardware will have current draw specs and if not just make an estimate on the generous side for the device.

The latter option is probably the best - I estimate we might have around 4,000W of power drawn, total, in that cupboard. Does that mean I simply need to get a 4,000VA UPS? I've tried that calculator linked to above, but when I input 4,000W it gives me a product priced at around £8,000, which is rather more than we can afford...

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David Hicks

[dhicks]

This UPS should suffice, we always recommend APC for their reliability: SUA1500RMI2U

Okay, thanks. I think we might need more than 1,500VA (does maximum power draw of server in Watts translate simply to VA rating of UPS?). Would it be better (and cheaper) to buy a single, larger UPS, or to use two of those 1,500VA devices? How much heat do they put out? How heavy are they - we don't have a proper rack in the cupboard, just a coffee table, which I don't think is going to be up to holding a UPS. Could they stand under the table on the floor?

We also recommend a management card to allow graceful shutdown of all servers

I currently have a PC with a cheap USB temperature sensor and a serial link to a UPS. If the power goes off or the temperature goes above a given limit for more than a minute then the PC turns off. I then have an application that pings that PC every minute or so - if it doesn't get a repsonse it uses SSH to shut down first virtual machines and then their physical hosts. What advantages does your management card offer over such a system?

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David Hicks

[richardp]

It really depends on what you want the ups to do I think. Do you simply want it to run long enough so that there is enough time to trigger and shutdown everything or do you want to run everything for X minutes in the hope the power will return or a generator will kick in? I would also recommend APC for their reliability which however does come at a price. Also some ups have a built in temperature sensor to monitor the environment for you, it all comes down to how much you have to spend as there is little point in looking at a high end ups at £10,000 when all you have to spend is £1000.

[dhicks]

Do you simply want it to run long enough so that there is enough time to trigger and shutdown everything

Yes, that's it - 10 minutes runtime is all that's required, really.

Also some ups have a built in temperature sensor to monitor the environment for you

Our current Smart-UPS seems to have an internal temperature sensor to measure its own internal temperature, which isn't quite as useful. If you mean an add-on management card then see above for question regarding management card vs. £5 USB temperature sensor from eBay.

there is little point in looking at a high end ups at £10,000 when all you have to spend is £1000.

Under £1,000 is more like it. How practical is making your own UPS out of car batteries?

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David Hicks

[dhicks]

While we're dicussing server cupboards: just how flamable are computers these days - do you need fire supression? If so, will an automatic fire extinguisher as sold for boat engine rooms and similar be the most suitible thing?

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David Hicks

[dhicks]

we always recommend APC for their reliability

Just looking at the APC website and guide prices (I assume actual prices are a bit lower than this):

APC Smart-UPS 2200VA £589.00
APC Smart-UPS 2200VA 2U £829.00
APC Smart-UPS 3000VA £899.00
APC Smart-UPS 3000VA 2U £1,075.00
APC Smart-UPS 5000VA £1,925.00

Why are the 2U versions more expensive than the same capacity tower units? To get 4400VA of UPS power, should we simply spend £1,178 on two 2200VA tower units (27p per VA) instead of £1,925 on one 5000VA unit (39p per VA)?

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David Hicks

[dhicks]

Just looking at the APC website and guide prices (I assume actual prices are a bit lower than this)

Yes - Amazon have the SUA2200I for £460.

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David Hicks

[richardp]

I bought an APC SURT8000XLI approx 18months ago for a project for around £1500 on a special offer (ex VAT), having just had a look they seem to have doubled in price now. However this ups had to be wired into the mains supply on a new circuit which cost almost as much as the ups itself. This model comes with the management card and a separate temperature sensor module that you can place anywhere in your rack. I think the advantage of the management system over your PC with USB sensor is that its an all in one system, your not having to run an extra computer to achieve it and the software is probably a lot more flexible. I doubt anyone would recommend you try and build a ups out of car batteries either. :-) There is nothing wrong with your solution and if it allows you to protect your system within the budget you have then all the better.

[dhicks]

I think the advantage of the management system over your PC with USB sensor is that its an all in one system, your not having to run an extra computer to achieve it

Good point - does seem rather silly to run a whole PC who's job it is to stay switched on until something goes wrong.

and the software is probably a lot more flexible.

Well, no - the software is a Python script, which we can have do whatever we like. It needs to shut down VMs first, then physical servers.

I doubt anyone would recommend you try and build a ups out of car batteries either.

Sissies. No sense of adventure.

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David Hicks

[richardp]

Well, no - the software is a Python script, which we can have do whatever we like. It needs to shut down VMs first, then physical servers.

Yes sorry you are correct, it's been a long hot day, of course anything like a custom script will do anything and everything you want. I used to be in the same boat as you with a very small budget when I worked in the private sector and I remember having to come up with loads of cost saving solutions to problems, I sort of miss that a little bit and still find it hard to break the habit.

Sissies. No sense of adventure.

Ha ha true very true :-)

[Butuz]

I would reccomend you go with multiple smaller UPS's rather than one bigger one. I use 3 x SMARTUPS3000 2U with each server wired into alternate UPS's so that if one UPS fails it won't take any servers out. This seems a nice way of doing it and actually one UPS did fail just after its 3rd birthday and everything kept on running because the other 2 ups's took the load up. (this only works if your servers have two power supplies, whch most have nowadays).

Another reason is that small UPS's can each use a standard 13 amp socket, wheras one big monster UPS will require a 32amp dedicated ring main installed £££

I wouldn't reccomend creating your own UPS - it can be done and is not difficult but multiple 12v batteries wired in series AND paralel are extremely dangerous I wouldnt fancy having to go to court because a homemade battery shorted / exploded and burned the school down! Frankly I'd rather APC take the risk on that one for me!

Butuz

[dhicks]

I use 3 x SMARTUPS3000 2U with each server wired into alternate UPS's so that if one UPS fails it won't take any servers out.

That's a good idea, thanks. I doubt we'll be buying servers with redundant power supplies, though - we handle redundancy by having function mirrored between the two server cupboards, which gives us a good solution to handle a complete diasaster (fire, flood, etc) too.

Another reason is that small UPS's can each use a standard 13 amp socket

Good point. I think I'm going to be asking for half-a-dozen 2200VA UPS' - one for every couple of servers.

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David Hicks

[SYNACK]

How much heat do they put out? How heavy are they - we don't have a proper rack in the cupboard, just a coffee table, which I don't think is going to be up to holding a UPS. Could they stand under the table on the floor?

They don't put out too much heat, they are heavy little buggers though, a 2200VA rackmount is about 40KG, tower is about the same.

[dhicks]

They don't put out too much heat, they are heavy little buggers though, a 2200VA rackmount is about 40KG, tower is about the same.

Many thanks. Do I assume a 3000VA UPS is around a third heavier, then? I have to get these up a narrow staircase to an upstairs cupboard, so the 2200VAs are looking like the best option...

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David Hicks

[SYNACK]

Many thanks. Do I assume a 3000VA UPS is around a third heavier, then? I have to get these up a narrow staircase to an upstairs cupboard, so the 2200VAs are looking like the best option...

Yeap they get heavy quickly, I managed to rupture several discs in my back with the 2200VA one we have here when I installed it down low in the rack by myself without thinking. You should have two people at least to do it as they are also an awkward unbalanced weight with heavy batteries at the front and not so heavy chunks of copper (transformers) at the back. We put in a 5000VA later and I directed from a distance.

Going with the 2200VA ones is probably a good idea but does limit your reserves if your loads are unevenly distributed, having it all in one bigger unit means that you can have all devices share the output and shutdown in order of importance to give the best runtime. The larger units also often come with the management cards included which can make it cheaper and means you only need one management card. For max reliability it is best to have two UPSs that can each cover the full load connected to separate power feeds and each server connecting via dual PSUs to each. Most budgets including mine don't stretch that far though. We have 4 servers off a 2200VA APC 2xML380 G5, 1x ML350 and 1x ML110 which gives about 12 minutes runtime at 50% utilization, we have dual PSUs and the old unrelaible HP UPS hooked up to them so this shared the load out to about 30% utilization. Either UPS will carry the load but the HP one falls over if the wind blows the wrong way so it is up to the APC to all intensive purposes.

I think that there are some cases and or adapters that do allow for two standard PSUs to be connected in tandem to provide dual PSUs at a much cheaper price point. They appear to be difficult to find though from 5 minutes on Google anyway.