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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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