[mythtv-users] OT: apc backup

[Simon Hobson]

Stephen P Villano <stephen.p.villano at gmail.com> wrote:

> We had the converse, where uptime was mandatory in a DoD environment.
> The problem was, the building UPS worked great, but the racks of
> batteries were defunct. It took an outage that dropped the entire
> building and hence, all war communications going down for 12 hours to
> make replacing the defective batteries a priority.

Yeah, that seems to be a universal problem. One I have is that we've had no power cuts at all for some time - because of bits dying, we've been on bypass for a year or more, and I've recently rebooted some systems for upgrades that had uptimes of over a year. In fact, I think one was nearly 2 years :-)
Against that, spending money on power protection does not get much priority.

One the flip side, we have had some good cuts in the past. I think it was a few years ago when I'd recently finished something or other and wanted to "throw a switch" in the server room. I can't remember the exact circumstances.
But I said I wanted to do it, and several of us stood around discussing the risks and which customers we needed to inform first. Manglement weren't too happy about doing it during the day - but then I got to do it without any risk ! While we were talking, the lights went out and 7kW worth of servers all went very quiet, so I was able to flip the switch before we began a cold startup when the lights came back on.

> Then, the generator failed, as a water leak displaced the diesel in the
> underground tank...

I've read that the genny failing to work properly is a very common one - they seldom get tested properly under real conditions. Either the starter batteries are dead, there's a mechanical fault, it can't actually provide the power needed, contaminated fuel, or "old fuel". Over here there's an outfit that sells a service whereby they'll sell your genny capacity to the grid in return for STOR* payments. Two of the benefits they sell it on (apart from getting paid to have your genny around) are testing it under load** and turning over your fuel stock.

* Short Term Operating Reserve. It's plant that's generally rarely used, but needs to be there for fast startup for those "oh bother" moments at grid control. Such as 6pm on the coldest day of winter, when solar and windmills are doing SFA, and load is at it's highest (and in the UK we now risk having negative generating surplus), and something on the network breaks down.

** Few people have the ability to parallel the genny with the mains, that means a big changeover switch which drops power to the building when you operate it, and so no-one will allow a real test that actually loads up the genny. So it just gets started, run at fast idle for 10 minutes, then shut down.