I have had to troubleshoot many strange things like that over a 26 year
period for different companies. It isn't always the operating
environment or OS.
- In one case we traced it back to an arc welder producing RFI (radio
frequency interference). We had to use insulated wiring (low
capacitance, twisted pair, shielded wiring) to solve it. We had to
shorten the cable to the shortest length possible and make sure that the
ground connections on the cable were connected. There are usually
limits to how long a cable can be before you go over the limit. The
signal gets weaker and is therefore vulnerable to RFI at longer and
longer distances. That is why you have to lower the speed of line to go
over certain distances. Cables act like an antenna and introduce RFI
into a system. That is why many people will disconnect unused cables
from their computers.
- At one company they were using a coax cable from RADIO SHACK that was
NOT the exact cable required even though the cable plugged in just fine.
It didn't have the electrical characteristics that was necessary to
maintain a high quality signal and caused network crashes once a day.
- In another case it was a failing UPS producing flaky power.
- In another case, bad memory chips (determined by using a memory
testing program that runs overnight).
- One time, a company had power fluctuations due to large equipment on
the same line. We had to connect the computer to a dedicated line
(straight out to the power pole) to solve the problem.
- I don't know what area you are in, but some power companies balance
their loads at night, and this sometimes creates brief, momentary, power
outages that can effect equipment if you don't have a UPS.
- If the power is wired incorrectly, it can behave strangely. A toaster
oven will work just fine, but a sensitive computer will not. You have to
get one of those power outlet testing devices ($10) and plug it in and
look at the light readout. It will tell you if negative and positive are
reversed, or there is no ground, etc.
- A PM (preventative maintenance) might be in order. Sometimes dust
will build up inside of a case on the motherboard and short connections
out once in a while when there is enough ambient electricity to come
through it. In other words it receives and picks up energy like an antenna.
- Grounding the computer with your mind works in cases where there are
spiritual disturbances. I have had customers with spiritual problems
that cause my computer to crash at the exact moment they call. Or a
light bulb blows out at the exact moment. Grounding it with your mind
can dissipate negative energy if that is what is causing it. This
happens a lot when there is negative/angry/hostile people throwing
negative energy at the computer. Putting a carbon-filled anti-static mat
underneath the computer can help as well.
- I have seen problems due to overheating computer also. We have had to
add CPU heat sinks/fans, replace power supply fans, blow the dust out of
them, etc.
- Sometimes a line can pick up a control characters to pause the
output. In the old days it was only CTRL-S, but UNIX adds some
additional signals to the mix. Clearing the line and resetting it can
work in some cases.
- One good thing to do is keep a log of the crash each and every time.
You put the port, date, time, event, user, and any special process
running at that time. Over a period of time, you might see a pattern.
For example, something late at night suggests power problems. Something
first thing Monday morning, might be due to a brownout caused by the
powering up of large factory equipment. Find out when the weekly
cleaning people come in. I had a problem once with client that kept
having problems with their computer on Friday morning. It would crash
Thursday nights. I happened to be working late one evening for them, and
I watch a cleaning person walk up to the computer, unplug it, and then
plug in their vacuum cleaner and start vacuuming! They would finish
vacuuming, and then plug the computer back in.
If you still can't resolve it after trying/researching these things,
please post the problem again. Also, please let us know what it took to
fix it for our FAQ.
ROBERT NORMAN AND ASSOCIATES
23441 Golden Springs Dr., #289, Diamond Bar, CA 91765
(951) 541-1668
i...@keyway.net <mailto:i...@keyway.net>
http://users.keyway.net/~ice/ <http://users.keyway.net/%7Eice/>
Affordable UNIDATA programming services for PICK/BASIC, DATA/BASIC, UniVerse
Basic, UniBasic, R/BASIC, jBC.
On 1/16/2013 10:39 AM, Kevin King wrote:
We have a customer with a box as described in the subject that has recently
been experiencing something odd. Overnight, the system will just lock up
and stop responding. Normally there isn't anyone doing anything at night;
the backup runs, that sort of thing, but then some days when they come in
early in the morning the entire machine is unresponsive. Connecting with
telnet there is no login prompt, just a blank screen. It happened last
night and I've confirmed from the logs that the backup (which is using a
split mirror backup strategy) ran successfully and finished at 2:02am.
Sometime between then and 4am, when there really should not have been
anything going on, it just locked up.
Are there any logs that can be enabled on AIX to record some evidence for
these kinds of failures so we can figure out what's going on with this
machine?
-K
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