[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