Unexpected shutdown

[n j]

> Does it happened before, or does it happened everyday at 3 am, or is this the first time your box shutdown without explaination?

No, this is the first time this has occurred, that is what makes it
completely unexpected.

> If this is the first time, I would say there are many possibilities. Say an accidental quick push on power button or - humor me - the cleaning lady is with the conserve energy movement and thought your box just another forgotten-to-shutdown desktop, that alone could explain your mysterious shutdown incident.

The machine is located in a server room within a server rack with a
(detachable) panel on the front side of the machine (Dell Poweredge)
that is covering the power-off button. No cleaning lady is entering
the room, especially at 3 AM. Due to all the circumstances I had
described, I ruled out (physical) human factor as the cause of
shutdown.

The box has two independent AC power supplies, no hardware error is
found in RAC card logs, no other server (in the same rack/room) shut
down at that time. That is what leads me to believe that the problem
is software-related.

I know there are many possibilities out there, but I am pondering this
for the whole day and ruled out everything that came to mind. So, any
other ideas - even humorous - are welcome.

Thanks for the input in any case.

Regards,
-- 
Nino