Nut upsdev - Nov 2015 - Some thoughts on loss of communication

As a follow up on my last message, where I talked about loss of USB
communication with my Asium P700 UPS, I was thinking about some possible
improvements.?

1.? When communications are lost, instead of shutting down immediately why not
set a flag and then stop the driver and then restart the driver.? If
communication is not re-established, and the flag was set, then shut down the
system.? Perhaps this is already being done.2.? In my case, when the shutdown
occurs due to loss of communication, the NUT software tries to turn off the
UPS.? It can't do that because there is no communication.? This cause the
shutdown process to hang up for some period of time.? In my opinion this is not
good because the system may crash during that period when it is hung.? The
software should skip trying to shut off the UPS and just execute a normal
shutdown.
Just my thoughts.? Maybe there is a way to configure exactly what I have
suggested and I just don't know how to do it.? LOL!
Viva la France !?I'm not irrational, I'm just quantum probabilistic.
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On Nov 21, 2015, at 2:06 PM, john hart <jsamcr at yahoo.com>
wrote:
> 
> 1.  When communications are lost, instead of shutting down immediately why
not set a flag and then stop the driver and then restart the driver.  If
communication is not re-established, and the flag was set, then shut down the
system.  Perhaps this is already being done.
This is not likely to be implemented any time soon. It is too dependent on
distribution-related things, like how the driver is launched.

Our preference is to fix the driver so that it reconnects itself, but the
maintainer of the blazer_* drivers has not worked on NUT for several years
(hence the move to nutdrv_qx).
> 2.  In my case, when the shutdown occurs due to loss of communication, the
NUT software tries to turn off the UPS.  It can't do that because there is
no communication.  This cause the shutdown process to hang up for some period of
time.  In my opinion this is not good because the system may crash during that
period when it is hung.  The software should skip trying to shut off the UPS and
just execute a normal shutdown.
NUT cannot foresee every kind of communication failure, and most of the drivers
already have timeouts built in. As a backup, the distribution startup/shutdown
scripts should probably have timeouts as well - this used to be implemented as a
delay between sending SIGTERM and SIGKILL.

-- 
Charles Lepple
clepple at gmail