Uninterruptible Power Supplies

[DeathKitten]

Hello Everyone!

I have been meaning to get a UPS for my computer for a while. A friend recommends getting one from APC, and since I can get those at work (assuming our prices are competitive), I am likely to follow his advice.

What I'm hoping all of you can help me with is, while he's a full time Linux user too, my friend hasn't actually bothered to set his UPS to automatically shut down his computers in the event of a power outage, if the battery on the UPS is getting low. I was hoping that someone on the forums has ventured down this path and might be able to advise me on what's involved in setting it up, and if there are any features/settings/requirements I need to look for when selecting my UPS.

Any direct experience with a particular brand/model, even if it's outside the brand my friend advised me to get would also be welcome.

Thanks in advance for all help you guys can give me.

[dibl]

Re: Uninterruptible Power Supplies

@DK I got one of these after I sank a bunch of money into a new desktop system 3 years ago:

http://www.newegg.com/Product/Produc...82E16842107114

Arguably it's "overkill", but after spending $2500 on the good computer hardware at the time, it seemed wise to overkill the protection of it. Besides, is there really such a thing as "stays up too long" when the power goes out?

It has "beeped" loudly whenever I had a power outage, and seems to give me plenty of time to shut down the system. Although, after 3+ years, it's probably time to review the availability of replacement batteries. :P

It has the serial interface, and I have the right cable, but I confess to severe laziness when it comes to figuring out how to set up the auto-shutdown thing. I tend to shut the system down when I leave the house for more than a few hours, anyway, so I have never bothered to figure out how to set up monitoring and auto-shutdown.

[kevinc]

Re: Uninterruptible Power Supplies

UPS's are useful for computers, especially desktops which tend not to have batteries and are more essential for servers and other computers which you don't want going down unexpectedly.

The simplest type of UPS is basically a rechargable battery, charged by mains power, which switches from charging a usually full battery to providing power from the battery in the event of mains not being supplied. In most civilized places, this is likely to be for a brief time and the return of mains triggers the UPS to switch back to charging the battery and providing power.

The two main factors you need to consider is how much power does your computer (and any periferals) use (go for the maximum) and for how long do you want to provide power?

For example. Your computer is say, 500 watts. You want power for a maximum of two hours.
2 * 500 = 1.0 kWhr

You can use amps instead of watts
2 hr * 5 amps = 10 amp hours

I use two batteries of 100A hr each which gives a theoretical 200 Ahr, but realistically 100 Ahr,
charged by a solar panel which provides enough power for my needs. (no city power)
Your milage may vary.

As for turning your computer off when the battery is low, sorry, I use manual shutdown not automatic.

[GreyGeek]

Re: Uninterruptible Power Supplies

At work we had individual UPS on each server. At least two, that I know of, failed to protect the server when the power failed. After those failures the IT dept switched to a big bank of batteries that had a trickle charger and more expensive monitoring and control systems. When cells in each battery in the bank arced over or opened, an audio warning is sounded and an email is sent. The system can be controlled remotely via a VPN.

When I ran Windows a USP is necessary. Even when I ran a Linux desktop I used an UPS. It's little green light glowed steadily, reassuring me that it was ready to leap into action. I tested it on occasions and it seemed to work. Mine was a little 500W device that would keep my desktop up for five minutes. About the size of a #12 shoe box.

When I switched to the ReiserFS, which is a journaling system, I wondered what was the point of an UPS? So, I packed it away.

There were several times while I was writing code in my home office when thunder was rolling outside, and when lightening struck nearby I'd yank the power cord out of the wall. Each time I booted back up ReiserFS would replay its journal and restore my file system. Over the 3 or 4 years I ran ReiserFS I NEVER lost a byte of data.

After Hans Reiser was convicted of murder it put a question mark around his FS, so I switched to EXT3. The first time I tried it, on a fresh MEPIS install, it failed on first boot! I went back to ReiserFS and didn't retry it till Mandriva 2009 PWP. It was worked OK for my every since. One thing that EXT3 does that ReiserFS NEVER did on me was to run fsck after so many boots. IMO, EXT3 is nowhere near the file system that ReiserFS is. I am hoping that something equal to Sun's ZFS, or ZFS itself, gets into Linux. FUSE or USF isn't it, yet. There is one, But, Oracle now owns ZFS and, unfortunately, the coder who wrote "Butter FS" (BTRFS), which is supposed to be better than ZFS, works at Oracle. But, BTRFS is not ready for prime time, yet.

[DeathKitten]

Re: Uninterruptible Power Supplies

I leave my desktop on practically 24/7. This sprung from downloads that I'd have auto start at the time of night everyone else in the house would go to bed, and just the pride of being able to say "Well, my computer's had an uptime of xyx days!" Given that I usually wasn't gone for much longer than a full day's shift at work, I usually wasn't worried too much about sudden shut offs. Now I mostly leave it on because it's an older machine that takes a little time to start up, and I'm impatient in the morning, I want to check my email right away!

Now, with my boyfriend living a good hour and a half drive away (and that's with my admittedly faster than the speed limit driving habits), I will sometimes be gone for a day or three at a time. While I really should have had a UPS already, in light of my occasional extended periods of being away without actually turning off my computer first, a UPS would be a good piece of mind. Also factor in the area I live in will have random small power outages or flickers where the power will go off for all of five minutes at a time, and a UPS would be very useful in keeping me up through those sorts of hickups.

So far, you boys haven't provided me with information I didn't already have... GreyGeek's explanations and commentary about journaling systems effecting the need for a UPS or not aside. However, as I know there are lots of newbs crawling this forum, I know the information will be useful to someone else. Hopefully with my well selected title for the thread, we'll bring in people who need this information as well as people who have more information to contribute.

Meanwhile, I really should do some number crunching to see what sort of power draw my tower and at least one, if not both, of my monitors will provide. I know I'll need at least one monitor, but there's probably no real need to have the second monitor on the UPS, is there? I'll double check the information on both... but I suspect that the one which is just a monitor, without the TV tuner, will be the lower draw of the two, right?

[askrieger]

Re: Uninterruptible Power Supplies

I'm glad to see I'm not the only uptime freak on this site. I wouldn't use a desktop computer that wasn't hooked up to a UPS.

Personally, I strongly second the recommendation of APC (American Power Conversion), at least if you live in the US, where battery replacement deliveries are fairly easy. Just don't try to get things by air, we're talking LEAD/ACID batteries which do not fly well even though they are sealed.

Not only do they offer a wide selection of new and used UPSes, but they also have a web site which will tell you more than you ever wanted to know about computer power management. If you give them your email address, they will send you monthly technical essays which are always informative and sometimes useful.

[GreyGeek]

Re: Uninterruptible Power Supplies

......

While I really should have had a UPS already, in light of my occasional extended periods of being away without actually turning off my computer first, a UPS would be a good piece of mind.

UPS only keep your computer powered for 5 to 15 minutes. The whole purpose is either to give you a change to do a graceful shutdown, in the case of extended power outages, or to prevent power blinks, spikes, noise, etc., from doing damage to your computer and data. As you know, of course, expecting an UPS to keep supplying power to a computer for more than 5 or 10 minutes after the power has failed is expecting what a UPS cannot deliver.

So far, you boys haven't provided me with information I didn't already have... but as I know there are lots of newbs crawling this forum, I know the information will be useful to someone else. Hopefully with my well selected title for the thread, we'll bring in people who need this information as well as people who have more information to contribute.

With your background as a tech sales and support person I assumed as much. 8)

Meanwhile, I really should do some number crunching to see what sort of power draw my tower and at least one, if not both, of my monitors will provide. I know I'll need at least one monitor, but there's probably no real need to have the second monitor on the UPS, is there? I'll double check the information on both... but I suspect that the one which is just a monitor, without the TV tuner, will be the lower draw of the two, right?

You've got it all figured out correctly. Besides the second monitor you also do not need to plug in the printer to a USP! There are other devices which may require power to stay up through fluctuations or outages. I used an APC version of a UPS. Here is a URL which has a calculator that will help you chose the right size UPS for your situation:
http://www.apc.com/tools/ups_selecto..._query_string=

[askrieger]

Re: Uninterruptible Power Supplies

UPS only keep your computer powered for 5 to 15 minutes.

Umm, Urr, that seems to contradict both the reference at the APC site that you quoted and my own experience. If you use a UPS that is grossly over-powered, you can easily get several hours out of an affordable system. You're protecting a computer that probably cost significantly more than a kilobuck, not to mention a lot of "stuff" that would take you hours to days of work to replace. That time is valuable. How valuable, is up to you. Moreover, you don't have to replace your UPS when you replace your computer, all you need is a replacement battery every now and again.

I will agree that you probably shouldn't rely on a UPS if you're taking a long weekend during thunderstorm season even if you're an uptime freak. Although my system survived a drunken teenager plowing into a nearby utility pole while we were out.

The only unbreakable rule about UPS usage is "Never attach a laser printer to a UPS!"

[doctordruidphd]

Re: Uninterruptible Power Supplies

For what it's worth, I found these.

This is a howto:
http://tldp.org/HOWTO/html_single/UPS-HOWTO/#AEN187

Which points to these two projects that are ups monitoring demons. I notice that both software suites are in the karmic repositories:

http://www.networkupstools.org/

http://www.apcupsd.org/

Edit: at least the networkupstools site has a list of compatible ups's. Maybe the other one, too, but I didn't see it right off the bat.

hope this helps. I really SHOULD get one of these too...

[DeathKitten]

Re: Uninterruptible Power Supplies

......

While I really should have had a UPS already, in light of my occasional extended periods of being away without actually turning off my computer first, a UPS would be a good piece of mind.

UPS only keep your computer powered for 5 to 15 minutes. The whole purpose is either to give you a change to do a graceful shutdown, in the case of extended power outages, or to prevent power blinks, spikes, noise, etc., from doing damage to your computer and data. As you know, of course, expecting an UPS to keep supplying power to a computer for more than 5 or 10 minutes after the power has failed is expecting what a UPS cannot deliver.

I'm not looking for something that will keep me up through half hour power outages, I want something I can set up to shut down my computer when I've got aprox. 5 minutes of power left on the battery, regardless of if the battery gave me five to ten minutes to start with, or if it's able to keep me rolling on a full charge for an hour.

Quickly skimming the links provided by doctordruidphd, it looks like I might have enough information there to keep me happy for a little bit. I will spend a little more time spelunking through that and report back on what I find out. I may have a couple more days of sitting around at the dealership waiting for them to finish frelling around with my car and hopefully render her drivable without sending me to bankruptcy, so I suspect my UPS research project will be best furthered during that time period. Hooray for free wifi in the service and parts lobby.

[GreyGeek]

Re: Uninterruptible Power Supplies

UPS only keep your computer powered for 5 to 15 minutes.

Umm, Urr, that seems to contradict both the reference at the APC site that you quoted and my own experience. If you use a UPS that is grossly over-powered, you can easily get several hours out of an affordable system. You're protecting a computer that probably cost significantly more than a kilobuck, not to mention a lot of "stuff" that would take you hours to days of work to replace.
....

A UPS that would keep up a mini desktop, 17" LCD Monitor, modem and wireless router for 6 hours cost over $1,000. The average desktop today costs around $400-500. ReiserFS makes more sense. IF the power stays off so will the computer. When the power comes back on journal replay will restore the data. No charge. BTW, although I didn't mention it, EXT3 has journal replay too, and I've had to depend upon it while testing Karmic because it locked up my laptop so hard only a power cycle would restore control.

[askrieger]

Re: Uninterruptible Power Supplies

Ah, hah! Different assumptions. The ONLY thing you really need to have on the UPS is the computer. First of all, it's the most expensive component (at least in my system). Second, it's the only thing that takes hard work to replace (assuming you have, and use, an off-line data backup, e.g. an auxiliary hard drive). Everything else (or almost, everything else) can be on surge protected outlets; laser printer MUST be, monitor, backup drive, speaker system, and home router, can be.

I have never gotten around to trying RFS, although I have toyed with the idea. From what I've read ext4 is more recoverable than ext3, so I probably never will, but it's nice to know that the alternative exists. Is RFS still supported?

However, I think we're all agreed, (including DK) that if you leave your computer up but unattended for a three day weekend, your UPS alone won't save you, unless you're using the automatic turn-off software. Thanks to doctordruidphd for posting the required information.

[DeathKitten]

Re: Uninterruptible Power Supplies

All I wanted on the UPS was the tower and one of the monitors. I figure if my power's out, I have bigger concerns than posting on the forum here. Also, the modem is way off upstairs and across the house, so I wouldn't be able to put it on my UPS even if I wanted to. I figure if I need to network my laptop and desktop while the power's out, I should just have a crossover cable handy and learn how to patch the two together.

My network in this house is all weird. We've got an Apple Airport hooked to the DSL modem upstairs, and then I've got another Airport downstairs that my desktop is plugged into to receive signal from the other Airport. My laptop happily connects to either airport or the various expresses we have littered around the house. We're in a rental, and our part of the house is spread out weird, so running Cat5 for our network really wasn't a practical option.

Because I've seen it mentioned a couple times in this thread, and I don't understand the reason behind it, I'm going to ask. Why shouldn't one have a laser printer on a UPS? I don't have one myself, but it would be handy to know if I do get one (I have been eying an inexpensive model at work for printing out my various black and white documents that come up from my writing and addiction to pen and paper gaming).

[kevinc]

Re: Uninterruptible Power Supplies

Laser printer use huge amounts of power for the electric heater - typically 1,000 Watts or more, while inkjet etcetera are much lower some under 100 watts.

[askrieger]

Re: Uninterruptible Power Supplies

Why shouldn't one have a laser printer on a UPS?

Actually, it's because laser printers generate heavy power surges at random intervals. I can't swear to the kilowatt number. This can damage the UPS if it's running on battery. I think I actually saw this in one of the technical articles at the APC site.

BTW, I looked under one of my desks and discovered that we also own a Belkin UPS. I must have gotten it as a throw-in on a computer purchase, back when I had employees who needed computers. I haven't had any trouble with it.