Date: Wed, 16 Oct 2013 11:54:41 +0100 From: Frank Leonhardt <frank2@fjl.co.uk> To: freebsd-questions@freebsd.org Subject: Re: UPS buying suggestion Message-ID: <525E7071.1080209@fjl.co.uk> In-Reply-To: <20131015200708.70057bba@X220.ovitrap.com> References: <CACo--msUpY-6r7MkuEvrPDpSVdFZyBotSA-eS7aLGMFDeq_vDQ@mail.gmail.com> <525D225B.7050205@fjl.co.uk> <20131015200708.70057bba@X220.ovitrap.com>
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On 15/10/2013 13:07, Erich Dollansky wrote: > On Tue, 15 Oct 2013 12:09:15 +0100 > Frank Leonhardt <frank2@fjl.co.uk> wrote: > >> On 15/10/2013 06:07, yudi v wrote: >>> I am planning on buying an UPS to protect my HP microserver >>> n40l<http://n40l.wikia.com/wiki/HP_MicroServer_N40L_Wiki>, >>> it will be running FreeBSD 9.2 RELEASE. >> As to the "compatibility", I do the myself. All I want it to do is >> shut down gracefully if the power fails - nothing more. And this is >> how I do it: >> >> All servers are, by definition, connected to the network. They can >> ping equipment nearby (just do it from a shell script). If they ping > this is real cool. You can then also control when to shutdown. This is > the problem I have here. I will not shutdown for a few minutes of no > power. You certainly can - you can send warning emails, log short power cuts and do whatever you want in a script. One thing I do is write a file to a share on a Windows box and have it shut down when it sees the file exists. >> As to the "run time", there are lies, damn lies ans statistics. I >> once tested a load of them for an article in PC Magazine and took > Did you get always new devices or the devices these companies ship from > magazine to magazine? > > Batteries age also by the number of charge-discharge cycles. Actually, battery capacity can also improve if cycle them. With most battery technologies the peak capacity develops after several cycles. How deep do the cycles have to be? That's a really good question! Lead Acid is different to NiCd which is different to NiMH which are different to each of the the many Lithium types. The problem I had with equipment reviews wasn't usually getting a knackered sample; quite the reverse in fact as manufacturers would sometime send kit that was "review tuned" in order to get better coverage and they knew with thrash whatever we had to test. A favourite trick was to find a server hard disk in a desktop. Standard equipment? I don't think so. Favourable editorial mentions were worth tens of thousands in advertising. Those were the days! I ended up writing a lot about batteries (too geeky for most hacks, and once commissioning editors got the idea...) The one thing I learned from the experience is that most of what you think you know about batteries is closer to folk lore. Bearing this in mind, I believe that leaving the gel lead-acid batteries float-charging in a UPS kills them over time, whether you cycle them or not. (As does leaving them to self-discharge on a shelf for years). Hence my suggestion to change them every couple of years in critical applications. Batteries are cheap, as long as you don't need weird sizes. Trashed hard disks are expensive! Regards, Frank.
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