[mythtv-users] Netbook as low-power combined back-end / front-end?

[Terjesen Jens Peder]

-----Original Message-----
On: 28. august 2012 8:07 rsh1k wrote:

On Tue, Aug 28, 2012 at 1:44 AM, Simon Hobson <linux at thehobsons.co.uk> wrote:

> Lastly, what sort of climate are you in ? Or more importantly, what 
> sort of temperatures does your UPS live in ? The VRLA (Vale Regulated 
> Lead Acid) batteries they use really don't like heat and despite 
> what's claimed about them they will dry out. If the batteries are 
> still running, it may be worth prising the cover off to get at the 
> rubber caps on the cells, and putting a tiny amount of distilled water 
> in - only a couple of ml, a small syringe is good for that - to rehydrate them and see if they improve.
>
> --
> Simon Hobson

I was out in the Northwest USA at that point, so I doubt it was heat
or cold that killed it.   I didn't check the battery acid levels, but
to be honest, I wasn't particularly thrilled with it even when it was
new.   I bought it (a mid-grade APC unit) because our building had a
lot of small power fluctuations... 1/2 second brownouts, that sort of
thing.   About once every week and a half, I would come home from work
to find the computer off.   With the UPS, the computer would receive a
signal via USB when the battery level was low, and do a controlled shutdown, preventing any issues with filesystem or database corruption.  It seemed like a good setup.

But in practice, it ended up being rather annoying.  At best, when new, it had about 15 minutes of runtime and would continue on with only a brief warning squeal to indicate that the power had been
interrupted.   But once the batteries started to weaken, it would
trip, estimate that it had <5 minutes of runtime left, and signal the computer to turn off almost immediately.  So even those short power
dips would end up turning the computer off completely.   I started
coming home from work and finding the computer off more often than
before.   Even turning on a hair dryer in the bathroom would turn off
the TV!

I thought about getting new batteries, and I thought about upgrading to a bigger UPS.  But in the end, I didn't want to spend hundreds of $$$ and have a massive UPS that was twice the size of my computer, all
sitting on display in the living room.   I got rid of that UPS when I
moved...

- rsh1k
-----Original Message-----

To me that looks like a less than optimal setup for a UPS.

I have a small UPS with only about 10 - 15 minutes of runtime that works perfectly well for my combined BE/FE.

It is configured to signal the computer to turn off 30 seconds after power loss.
This prevents short power dips from shutting down the computer.

My BE/FE uses about 30 seconds to shut down, so the UPS is also configured to shut off the power 60 seconds after signaling the computer to shut down.

The BIOS is set to start the computer at return of power.

So short power dips does not influence the BE/FE at all.
Longer power outages leads to a controlled shutdown, and automatic startup of the BE/FE when power returns.
This setup also prevents deep discharge of the UPS battery.

I also have one lamp connected to the UPS which gives me 90 seconds emergency light, enough to go fetch a torch.

Jens