Date: 27 Jun 2001 08:50:23 +0930 From: Andrew Reid <andrew.reid@plug.cx> To: Ted Mittelstaedt <tedm@toybox.placo.com> Cc: freebsd-questions@FreeBSD.ORG Subject: RE: FreeBSD and surviving unclean shutdowns Message-ID: <993597623.1681.6.camel@percible.alfred.cx> In-Reply-To: <001e01c0fe27$69f334e0$1401a8c0@tedm.placo.com> References: <001e01c0fe27$69f334e0$1401a8c0@tedm.placo.com>
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On 26 Jun 2001 03:04:40 -0700, Ted Mittelstaedt wrote:
> You want to get a UPS that has a signal cable and set up
> your FreeBSD server to gracefully shut down. However, if you
> already have a UPS that for budgetary reasons you can't replace,
> then it's rediculously easy to add signalling to it. All you need
> to do is get a 120 volt (or 220 volt if your in Europe) relay
> from any electronics supplier and wire this on your UPS AC input power.
> Then take the normally closed contacts (which will be open when the
> AC to the UPS is on) and connect one to DTR and the other to CD
> (Carrier Detect) on an unused serial port.
Yeah, we've got an APC SmartUPS 3000 which features one of those serial
ports, so I'm going to set it up now. Why didn't I have it setup before?
Dunno. My fault, but I don't know why I didn't. We live and learn, I
spose :-)
> Then you write a simple script that starts by attempting to open
> the serial port callin device. On successful open it issues
> the command "shutdown -p" (obviously your server must support
> -p)
I think I'll have a look at NUT which does just this. As well, NUT tells
the other servers to 'call it a day'.
> The only problem with all this is that once the system shuts down it
> won't automatically power back up. (if it's a soft power up system)
Only one of our servers has this function. It's an Intel Server board
and it seems to be one of the few Motherboards that I've been able to
source that features the 'auto-on' when there's power. Some of the
workstations around here turn on automatically, but I think that's from
being dropped or something :-)
> It might also be possible, depending on your UPS, to add signalling by
> measuring the 12 volts directly across the battery terminals. What you
> would do
> is get a 12 volt relay that uses the lowest current that you can find,
> then wire this in series with a 100 Ohm potentiometer directly across the
> battery terminals. Then with UPS batteries fully charged, you unplug
> the UPS from AC and while it's running on battery power, you adjust the
> potentiometer until the relay contacts open, then back the adjustment up
> somewhat. The idea here is that with ordinary lead-acid UPS batteries,
> as they are discharged their output voltage gets lower and lower until the
> battery is completely discharged. But, this may not work because the
> relay draw may interfere with the UPS charging circuit, (making the UPS
> think
> the batteries are never fully charged) or the UPS may decide to shut down
> before the battery voltage has changed enough for the relay to open. Any
> experimentation that anyone does in this area would be most interesting.
Thanks for the detailed explanation(s). It was quite an interesting
read. I think I'll leave it to the built in Serial cable so I don't void
the warranty.
- andrew
--
void signature () {
cout << "Andrew Reid -- andrew.reid@plug.cx" << endl ;
cout << "Cell: +61 401 946 813" << endl;
cout << "Quidquid latine dictum sit, altum viditur" << endl;
}
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