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A.1 How to Determine What Is Causing a Problem
==============================================
When you run into a problem, the first thing you should do is to find
out which program or piece of equipment is causing it:
* If you have one of the following symptoms, then it is probably a
hardware problems (such as memory, motherboard, CPU, or hard disk)
or kernel problem:
* The keyboard doesn't work. This can normally be checked by
pressing the Caps Lock key. If the Caps Lock light doesn't
change, you have to replace your keyboard. (Before doing
this, you should try to restart your computer and check all
cables to the keyboard.)
* The mouse pointer doesn't move.
* The machine doesn't answer to a remote machine's pings.
* Other programs that are not related to MySQL don't behave
correctly.
* Your system restarted unexpectedly. (A faulty user-level
program should never be able to take down your system.)
In this case, you should start by checking all your cables and run
some diagnostic tool to check your hardware! You should also check
whether there are any patches, updates, or service packs for your
operating system that could likely solve your problem. Check also
that all your libraries (such as `glibc') are up to date.
It's always good to use a machine with ECC memory to discover
memory problems early.
* If your keyboard is locked up, you may be able to recover by
logging in to your machine from another machine and executing
`kbd_mode -a'.
* Please examine your system log file (`/var/log/messages' or
similar) for reasons for your problem. If you think the problem is
in MySQL, you should also examine MySQL's log files. See
log-files.
* If you don't think you have hardware problems, you should try to
find out which program is causing problems. Try using `top', `ps',
Task Manager, or some similar program, to check which program is
taking all CPU or is locking the machine.
* Use `top', `df', or a similar program to check whether you are out
of memory, disk space, file descriptors, or some other critical
resource.
* If the problem is some runaway process, you can always try to kill
it. If it doesn't want to die, there is probably a bug in the
operating system.
If after you have examined all other possibilities and you have
concluded that the MySQL server or a MySQL client is causing the
problem, it's time to create a bug report for our mailing list or our
support team. In the bug report, try to give a very detailed
description of how the system is behaving and what you think is
happening. You should also state why you think that MySQL is causing
the problem. Take into consideration all the situations in this
chapter. State any problems exactly how they appear when you examine
your system. Use the `copy and paste' method for any output and error
messages from programs and log files.
Try to describe in detail which program is not working and all symptoms
you see. We have in the past received many bug reports that state only
`the system doesn't work.' This doesn't provide us with any information
about what could be the problem.
If a program fails, it's always useful to know the following
information:
* Has the program in question made a segmentation fault (did it dump
core)?
* Is the program taking up all available CPU time? Check with `top'.
Let the program run for a while, it may simply be evaluating
something computationally intensive.
* If the `mysqld' server is causing problems, can you get any
response from it with `mysqladmin -u root ping' or `mysqladmin -u
root processlist'?
* What does a client program say when you try to connect to the
MySQL server? (Try with `mysql', for example.) Does the client
jam? Do you get any output from the program?
When sending a bug report, you should follow the outline described in
bug-reports.
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