Debugging a hanging 5.4 system
Michael R. Wayne
wayne at staff.msen.com
Wed Jan 25 10:40:11 PST 2006
We've got a system running 5.4-RELEASE-p8 that occasionally
hangs while dump is running. I suspect it's something to do
with the SCSI controller hanging:
ahc0: <Adaptec aic7896/97 Ultra2 SCSI adapter>
because the machine remains pingable and I can hit <CR> on the
serial console and keep getting login prompts until I enter a
username at which point the machine ceases to respond.
I've compiled a kernel with
in preparation for the last crash. There is a portmaster hooked
to the serial port so that I can telnet to it and break to the
debugger. Obviously, I will not be able to create a crash dump.
My question is what specific DDB commands I should use when the
system is hung so that I can generate sufficient information to
create a useful PR. Any other hints/tips would also be appreciated.
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