[PLUG] How do I debug Linux crash

[Vincent Yau]

Hi:

My Linux box crashed twice last week and I could not figure
out what had happened.  Any tips/pointers much aprpeciated.
Here is what happened:

The box is running kernel 2.6.6.  I got it through Fedora 2.
It has been running fine for at least a year and a half.  The box
is a P4 2.4 Ghz 800 Mhz FSB.  One GB of memory.  Recently,
we have setup and run Oracle 9i on it.   There are about 2 Oracle
users and they do run pretty heavy database reports out of the Oracle 
instance
installed on this box.  Last Thursday, it was business as usual and there
were some sort of Oracle work going on.  I had to burn a CD and
burning at a lower speed would take up less resources.  So I was burning
my CD at speed 8 using cdrecord.  All of a sudden, my screen turns blank, 
the
CD ejected itself but the CD burning job wasn't finish.  I cannot ssh or 
telnet into the
box and console screen is blank.  I had to press the reset button.  When it 
finished
booting, I looked into /var/log but could not find anything indicating 
problems in
any of the log file.  Then I looked at /etc/syslog.conf and found
that kernel.* wasn't being logged to anywhere.  So I added kernel.* into 
/var/log/messages.
Then I restarted Oracle and informed the 2 users to resume their work.     I 
then began
to burn the same CD that did not go through.  This time, I lowered the speed
to 4.  Again the same crash behavior appeared about 10 minutes later.  After
the box was rebooted, I once again look into /var/log for any clue.  And 
again,
nothing relevant was found.   There aren't anything major
running other than Oracle and my cdrecord process.  I have used cdrecord
on this system before and it worked fine.  Oracle has been running
for two months already and the box never crashed until last Thursday.


My questions:
Is there somewhere other than /var/log I should go and look for clues
as to what happened?  Is logging kernel.* inside /etc/syslog.conf enough
to debug this type of situation?

Luckily, the box is running just fine ever since.  I was able to burn the CD 
that I needed.
Nonetheless, I still want to know how I can debug so I know what to do
next time.

Thanks in advance for any tips...

--Vincent

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