A power fault diagnostic mechanism for a computer system having a power system
that includes a controller. A variable is recorded in a non-volatile memory associated
with the power system. The variable assumes a first state when the computer system
is powered on and operating. The variable remains in the first state until it enters
a second state when the computer system is powered off in response to a power-off
request. The controller operates in a standby mode when the computer system is
powered off. Upon being powered up, e.g., after a utility power disturbance, the
controller reads the variable in the non-volatile memory. This allows determination
of whether a disturbance has occurred, even when the computer system was powered
off. The controller maintains a local error log based on the variable accessed
from the non-volatile memory. A system error log is updated by the operating system
using the local error log.
