--- On Thu, 3/31/11, Charles Lepple clep...@gmail.com wrote:
From: Charles Lepple clep...@gmail.com
Subject: Re: [Nut-upsuser] Startup timing issue with CyberPower CP425HG UPS
To: Arun twelvefortyf...@yahoo.com
Cc: nut-upsuser@lists.alioth.debian.org
Date: Thursday, March 31, 2011, 7:25 PM
On Mar 30, 2011, at 9:46 PM, Arun
wrote:
I'm not sure how to fix this, other than to perhaps
start the ups service from the udev rules file if a known
USB UPS device has been found, but that seems like a rather
ugly way to go about this. Does anyone have any thoughts?
I have had a sneaking suspicion that in some situations,
starting a USB driver from hotplug or udev might work
better, and this is definitely one of those cases.
Yeap. IMO an even better option (if technically feasible) would be for the
driver to try and reconnect to the UPS every few seconds. It seems to do this
well if it loses connectivity after having established the initial connection,
but not at all at startup.
Before you get too far into this, you probably want to make
sure that when power returns, your UPS will wait until the
battery is charged to some threshold before powering on its
outlets. Otherwise, if the power goes off-on-off (with a
shutdown after the first power failure), the UPS might try
to start the computer up with a discharged battery, and due
to the delay in connecting to the UPS, NUT would not get the
low battery signal in time to shut down properly the second
time.
Good point. Unfortunately this UPS is not very fancy, and immediately powers on
its outlets when the power resumes.
The other trick is that the current NUT USB drivers will
attempt to reattach to a device if it disappears. Especially
during testing, it is helpful to be able to unplug and
re-plug the UPS into the USB port. For this to work, the
udev script could kill the driver which is waiting around
for the UPS to come back. (That would only do the right
thing on a single-UPS system.) Alternatively, you could
check in the udev script to see if any of the USB drivers
are running (look for the PID files, and run kill -0 to
see if the process is still around without actually
terminating it).
I did a couple of tests and it looks like driver recovers well once the UPS is
reconnected to the system. Unfortunately it doesn't seem to try to reconnect at
all at startup.
On the other hand, you can also look into whether your
startup scripts have configurable dependencies, and tell the
NUT init.d script to start after the USB service has fully
initialized. Not sure how that works in Fedora.
Me neither. I don't know if there is a USB service per se in Fedora; USB
devices announce themselves individually as they are connected to the system.
Most USB devices (the kbd, mouse, another UPS I tested) register with the
system *before* the init.d script starts, it's just this one UPS that registers
much later for some reason.
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