[Nut-upsuser] APC SmartUPS switches off with no reason

[Ivan Kuznetsov]

Hello

One our customer has two Linux HP-branded servers powered from "clasic"
APC Smart-UPS 2200 RM 2U (p/n SUA2200RMI2U). It is connected to first
server via RS232c port with APC-branded cable. We have installed NUT
2.6.4 with apcsmart driver. This setup works fine for months. Two weeks
ago all the hardware powered from the UPS started to switch off
occasionally while on line power. The UPS switchs off too and need to be
turn on manually. No any warnings or so logged by NUT. UPS load is
<25-30%, battery is ok. With disconnected control cable the UPS forks as
desired, no switch offs for 6 days. When customer connects the cable
back the UPS switchs off after ~12 hours. It looks like the UPS recives
'instant poweroff' command via interface with no reason

What can be a diagnostic procedure?



--
Regards, Ivan Kuznetsov
SOLVO ltd

[Ivan Kuznetsov]

Customer says the control cable is APC 940-0024D

[Matus UHLAR - fantomas]

Post by Ivan Kuznetsov
One our customer has two Linux HP-branded servers powered from
"clasic" APC Smart-UPS 2200 RM 2U (p/n SUA2200RMI2U). It is connected
to first server via RS232c port with APC-branded cable. We have
installed NUT 2.6.4 with apcsmart driver. This setup works fine for
months. Two weeks ago all the hardware powered from the UPS started
to switch off occasionally while on line power. The UPS switchs off
too and need to be turn on manually. No any warnings or so logged by
NUT. UPS load is <25-30%, battery is ok. With disconnected control
cable the UPS forks as desired, no switch offs for 6 days. When
customer connects the cable back the UPS switchs off after ~12 hours.
It looks like the UPS recives 'instant poweroff' command via
interface with no reason
What can be a diagnostic procedure?

Hello,
20 years ago I was working with APC Smart UPS (1500 iirc) and I have noticed
this behaviour:

when power fell off with cable plugged in (powerchute not configured), the
UPS turned power to my computer a few seconds after the outage.

When the cable was not plugged in, the UPC did hold the power until it
discharged.

Therefore I think that the APC UPS needs to communicate with the computer
when it's connected and it loses input power, otherwise it shuts output
power down...

I feel there something strange about APC UPS...