Gus Wirth wrote:
Gregory K. Ruiz-Ade wrote:
So, in a similar vein to the other hardware debugging issues that
have been discussed here, does anyone have recommendations for
debugging when a system spontaneously reboots?
The basic result is as if someone hit the reset button. Now, unless
the reset button on the case is actually triggering somehow (why
would it?), what could be causing this?
It's driving me absolutely batty, because it started on Tuesday,
apparently in the morning:
[EMAIL PROTECTED](pts/2):~ 4 > last reboot
reboot system boot 2.6.20-16-generi Wed Oct 3 07:20 - 11:13 (03:53)
reboot system boot 2.6.20-16-generi Wed Oct 3 00:56 - 00:57 (00:00)
reboot system boot 2.6.20-16-generi Wed Oct 3 00:47 - 00:54 (00:06)
reboot system boot 2.6.20-16-generi Wed Oct 3 00:31 - 00:31 (00:00)
reboot system boot 2.6.20-16-generi Tue Oct 2 23:30 - 00:31 (01:01)
reboot system boot 2.6.20-16-generi Tue Oct 2 23:19 - 23:29 (00:09)
reboot system boot 2.6.20-16-generi Tue Oct 2 21:24 - 23:29 (02:05)
reboot system boot 2.6.20-16-generi Tue Oct 2 11:47 - 23:29 (11:42)
reboot system boot 2.6.20-16-generi Tue Oct 2 10:46 - 23:29 (12:42)
reboot system boot 2.6.20-16-generi Tue Oct 2 09:46 - 23:29 (13:42)
reboot system boot 2.6.20-16-generi Tue Oct 2 08:46 - 23:29 (14:43)
reboot system boot 2.6.20-16-generi Tue Oct 2 07:46 - 23:29 (15:43)
I've checked last month's wtmp for reboot entries, and there's
nothing aside from when I know I've restarted the system.
There are numerous things that can make a system reboot but the most
common one I have come across is power supply problems. Despite the
fact that you have a new system, all it takes is one little burp from
the power supply to cause the reboot. Even if you have a brand name
power supply, it is suspect.
Troubleshooting the power supply requires that you either borrow or
make a power supply monitor. The monitor needs to check the +5VDC, the
+3.3VDC and +12VDC lines. I don't think anything uses the -12VDC line
any more except maybe the RS-232 serial port. The power monitor is
basically a simple comparator that will switch and stay switched when
the voltage drops below a preset value. I think about two dollars
worth of parts could make one, not counting the connector cable.
Could a computer be run directly from a car battery (with appropriate
voltage drops)? I thought maybe it could except for the negative
voltages. Why does a UPS have to supply AC to the PC when the PC just
converts it *back* to DC? I like the idea of having the computer
running directly from a car battery on a battery charger set for a
trickle charge. If the computer is the only thing running off the
battery, then it should be able to stay up for several hours of outage
before it runs out of spark. And it should survive longer if it doesn't
have to convert to AC and back to DC again, right? A voltage monitor
could signal the PC to shut down. A Myth machine would never miss a
recording because of a mere power outage (assuming the necessary cable
equipment had sufficient UPS also).
I was able to run a video cassette player and a 13" color TV on a car
battery (thru an inverter) for more than 3 hours before the battery was
too low to start my truck. The TV took 85 watts and the VCP took 16 watts.
Intermittent problems are always harder to fix than a complete
failure. It would be nice if you could have a log of everything
running over say a 24-HR period before a spontaneous reboot. For
example, run a cron job every minute to document all running processes
and monitor memory. Have the job call sync to flush the buffers to
disk, or even better log everything remotely.
One thing to try is to set the BIOS to leave the computer off on power
failure. Right now you can't distinguish between a reboot caused by
power interruption vs a reset signal/hardware/software fault. Maybe
you'll get lucky and find that the power is glitching and not the
computer. I had this happen once when my neighbor was using an arc
welder for about a week every night around 8 pm. Alternatively, see if
you can borrow a UPS if you don't have one and see if it helps.
I remember having one customer who kept bringing his computer in for
repair because of strange problems, but we never saw the problems he
described. In fact, we never saw *any* problems on it. We sold him a
line conditioner and all his problems went away. (The whole time, SDG&E
*swore* that their power tested clean. The line conditioner clearing up
the problems proved them wrong.)
--
Ralph
--------------------
If we didn't have ambiguity in the language we would not have good crossword
puzzles.
--carl lowenstein
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