Uninterruptible Power Supplies

[supermandead]

Hi all, i am just wondering with large scale farm, do you use a Uninterruptible Power Supplies in case of power surge? thank you.

[adamas]

Mobile nuclear reactor?

[Zeronic]

Yes, a UPS is a very useful thing to have between your farm and the wall. Some of the higher grade ones help keep the voltage very clean. Plus depending on how large of scale, safely power down the farm in the event of a Grid Failure.

[Inaba]

No, large farms far outpace all but the most expensive UPSs, making your ROI go into the toilet, so most large farms do not run UPSes.

[Epoch]

No, large farms far outpace all but the most expensive UPSs, making your ROI go into the toilet, so most large farms do not run UPSes.

Inaba is correct. Generally the cost-vs-benefit of a UPS does not make it worthwhile for a bitcoin mining operation. For a UPS to be cost-effective, the extra up-time it provides during its serviceable life would have to offset its purchase cost.

Let's take a simple example. Say you buy a cheap $50 250W UPS like the APC 450ES to power your Radeon 5870 miner. The 5870 plus host PC would use approximate 200-250W while mining. That UPS would last no more than 3 minutes with such a power draw (http://www.apc.com/resource/include/techspec_index.cfm?base_sku=BE450G).

How much BTC can that 5870 mine in 3 minutes? 400Mhps will currently mine approximately 0.29 CENTS in 3 minutes (closer to 0.2 CENTS after subtracting power costs). http://www.alloscomp.com/bitcoin/calculator.php

So in order to pay back your $50 UPS, you would need to go through 25000 3-minute power outages. That's the equivalent of 1 outage per hour, every hour, for the next 3 years. Do you think that likely?

A Radeon 5870 isn't the only option, of course. You can run these numbers with whatever UPS and whatever mining equipment you want, including FPGAs. I don't believe you would find a scenario in which a UPS would be cost-effective.

Of course a UPS has other benefits such as line conditioning, which may save your equipment from high-voltage damage. Exactly what that is worth, and the probability of such damage happening, is difficult to say. For some, this peace-of-mind may be worthwhile. But if you are mainly concerned with spike protection and not up-time, then a simple $5 surge protector will suffice.

[Zeronic]

No, large farms far outpace all but the most expensive UPSs, making your ROI go into the toilet, so most large farms do not run UPSes.

Of course a UPS has other benefits such as line conditioning, which may save your equipment from high-voltage damage. Exactly what that is worth, and the probability of such damage happening, is difficult to say. For some, this peace-of-mind may be worthwhile. But if you are mainly concerned with spike protection and not up-time, then a simple $5 surge protector will suffice.

This is why I have UPS on all my systems, thou I'm a server admin, so it in my nature to want to protect my system.

[Inaba]

Understandable... but your servers don't draw 1400w and 12 amps 24/7 either

[lemonz]

No, large farms far outpace all but the most expensive UPSs, making your ROI go into the toilet, so most large farms do not run UPSes.

There are primarily two types of UPS, battery and mechanical (ie: flywheel).

As Inaba said, a UPSs for a large farm would add greatly to their costs, thus reducing any ROI they are experiencing.  And it's not just the hardware, but the cost to keep it charged, which is far less than an initial charge, but you're still paying for it.

I could see a short term solution of battery based UPS along with an emergency generator for a short while.  While running on disel or petroleum would not be profitable, it would allow a stopgap for short power outages (you'd have to do a cost/benefit analysis on time involved with powering down and back up your farm vs $6.50 of fuel for a couple hours¹.  A solar powered generator could also be used to trickle power to the UPS, extending the discharge time.

¹: http://www.dieselserviceandsupply.com/Diesel_Fuel_Consumption.aspx assuming 200 GHash/s (8x mini rigs @ 1250w = 10KW) would consume 0.9 gallons of diesel an hour.  At $3.60 a gallon, you're looking at about $6.48 for 2 hours.  This correlates to $2.40 for 2 hours for that same consumption on electricity at $0.12 per KW/h.  For me, it would be worth the $4.10 difference to not have to power down / up that farm.

[deepceleron]

As long as you set the machines' BIOS to turn on when power is connected or restored, there isn't much loss of income. Just test that you can pull the power cord, plug it back in, and the machine restarts and starts mining again with the startup scripts you have in place.

Also note that UPS's use VA rating, which is just a big lie like hard drive MB, one manufacturer does it and then all the others do it. A 1500VA UPS typically can supply 1000W, and do that for about 7 minutes before it shuts down. Here's one: http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=SMT1500RM2U. $600 for an extra seven minutes...

Also note the crap power that cheap and even not-so-cheap UPS units put out, you wouldn't want to plug anything expensive into this:

[Inaba]

No, large farms far outpace all but the most expensive UPSs, making your ROI go into the toilet, so most large farms do not run UPSes.

There are primarily two types of UPS, battery and mechanical (ie: flywheel).

As Inaba said, a UPSs for a large farm would add greatly to their costs, thus reducing any ROI they are experiencing.  And it's not just the hardware, but the cost to keep it charged, which is far less than an initial charge, but you're still paying for it.

I could see a short term solution of battery based UPS along with an emergency generator for a short while.  While running on disel or petroleum would not be profitable, it would allow a stopgap for short power outages (you'd have to do a cost/benefit analysis on time involved with powering down and back up your farm vs $6.50 of fuel for a couple hours¹.  A solar powered generator could also be used to trickle power to the UPS, extending the discharge time.

¹: http://www.dieselserviceandsupply.com/Diesel_Fuel_Consumption.aspx assuming 200 GHash/s (8x mini rigs @ 1250w = 10KW) would consume 0.9 gallons of diesel an hour.  At $3.60 a gallon, you're looking at about $6.48 for 2 hours.  This correlates to $2.40 for 2 hours for that same consumption on electricity at $0.12 per KW/h.  For me, it would be worth the $4.10 difference to not have to power down / up that farm.

Your math is a bit off.  The cheapest 10kw diesel generator I could find was $13,000, assuming you used it about 100 hours a year, it would cost you roughly $202.4 per hour to operate.  Of course, 100 hours a year is kind of ludicrous, and if you end up using it that much, you have problems far beyond the need for a generator.  Little more per hour than $2.40.

[lemonz]

Your math is a bit off.  The cheapest 10kw diesel generator I could find was $13,000, assuming you used it about 100 hours a year, it would cost you roughly $202.4 per hour to operate.  Of course, 100 hours a year is kind of ludicrous, and if you end up using it that much, you have problems far beyond the need for a generator.  Little more per hour than $2.40.

So is yours...

100 (hours) * $202.40 = $20,240

$20,240 - $13,000 = $7,240

$7,240 / 100 (hours) = $72.40 of diesel per hour!!

What you probably mean was:

100 (hours) * $2.05 ($3.25 cost of diesel per hour minus the cost of electricity you would have paid - $1.20) = $205

$13,000 + $205 = $13,205

$13,205 / 100 (hours) = $132.05 per hour.

Now still, the problem with the above calculations presume that (1) the generator has no value in 12 months and/or (2) the life of the generator is 100 hours. 

The fact is you could buy a generator used, make light use of that generator over 12 months and resell if for little to no loss.  Depending on market conditions, you could even make money on the generator. 

My point, however, wasn't to argue the cost of acquiring and operating a generator... but that if someone was interested in an alternative to an industrial UPS, there would be options.

(And yes, you could also sell a UPS, but you would have a far easier time buying and selling a generator than an industrial UPS!)

[Inaba]

Fair enough, I did not consider resale cost of the generator.  But there's really no scenario where it's financially viable to run a mining rig on a UPS/backup generator... at least not at the current market rates.  If rates return to the $30 territory, you'd have a much better ROI

$13,205 / 100 (hours) = $132.05 per hour.

  That' what I meant!

[lemonz]

Fair enough, I did not consider resale cost of the generator.  But there's really no scenario where it's financially viable to run a mining rig on a UPS/backup generator... at least not at the current market rates.  If rates return to the $30 territory, you'd have a much better ROI

$13,205 / 100 (hours) = $132.05 per hour.

  That' what I meant!

We're on the same page I was merely trying to shine some light on a possible solutions to an industrial UPS for maintaining uptime and protecting the hardware.  Thinking outside the box as it were...  It would not be profitable when running, but it would prevent the system from losing power if that's what one needed. And if the deadweight loss were only a couple dollars an hour, that might be worthwhile for an hour or two just for the convenience.

Thanks Inaba!

[Vandroiy]

Also note the crap power that cheap and even not-so-cheap UPS units put out, you wouldn't want to plug anything expensive into this:
(...)

A decent PSU shouldn't give in so easily. Better than a sudden power down IMO.

I use an uninterruptible power supply. But I'm not mining, and it wouldn't make sense for that. It's just to safely hibernate the system and flush all caches in case I lose power.

Works fine so far. Tested it a few times and indeed lost power once. The system auto-hibernated properly, and I could continue where I left off when power returned. I like this.